Top 3 Mistakes That Vue.js Developers Make and Should be Avoided

Top 3 Mistakes That Vue.js Developers Make and Should be Avoided

In this article, we will take a look at some common mistakes that developers new to Vue.js often make, and how they can be avoided to become a Vue.js pro.

In this article, we will take a look at some common mistakes that developers new to Vue.js often make, and how they can be avoided to become a Vue.js pro.

Vue.js is probably one of the most enjoyable Javascript libraries to work with. It has an intuitive API, it’s fast, easy to use and flexible. However, along with flexibility some developers tend to fall into small traps that might have a negative impact on the application performance or long term maintenance.

So let’s dive in and see what are some common mistakes that should be avoided when developing with Vue.js.

1 - Side effects inside computed properties

Computed properties in Vue.js are a very convenient way to manage state that depends on other state. Computed properties should be used to only display state that depends on other state. If you find yourself calling other methods or assigning other properties inside computed then you’re most likely doing something wrong. Let’s take an example:

export default {
  data() {
    return {
      array: [1, 2, 3]
    };
  },
  computed: {
    reversedArray() {
      return this.array.reverse(); // SIDE EFFECT - mutates a data property
    }
  }
};

If we try to display the array and the reversedArray , you’ll notice that both arrays have the same values

original array: [ 3, 2, 1 ] 
computed array: [ 3, 2, 1 ]

So what happened is that the computed property reversedArray modified the original array property because of the reverse function. This is a rather simple example which results in unexpected behavior.

Let’s look at another example:

Assume we have a component that displays price details of an order

export default {
  props: {
    order: {
      type: Object,
      default: () => ({})
    }
  },
  computed:{
    grandTotal() {
      let total = (this.order.total + this.order.tax) * (1 - this.order.discount);
      this.$emit('total-change', total)
      return total.toFixed(2);
    }
  }
}

We created a computed that displays the total price including taxes and discounts. Since we know that the total price changed here, we might be tempted to emit an event upwards to notify the parent component of the grandTotal change.

<price-details :order="order"
               @total-change="totalChange">
</price-details>

export default {
  // other properties which are not relevant in this example
  methods: {
    totalChange(grandTotal) {
      if (this.isSpecialCustomer) {
        this.order = {
          ...this.order,
          discount: this.order.discount + 0.1
        };
      }
    }
  }
};

Now let’s assume that in a very rare case when one of our customers is special, we want to give him an extra 10% discount. We might be tempted to modify the order and increase its discount.

This, however will result in a pretty bad error

What actually happens in this case is that, our computed property get’s “re-computed” every time in an infinite loop. We change the discount, the computed property picks this change and recalculates this total and emits the event back. The the discount is again increased which triggers another computed recalculation and so on infinitely.

You might think that it would be impossible to do such a mistake in a real application, but is it ? Our scenario (if it happened), would be really hard to debug or trace because it requires a “special customer” which may appear only once in every 1000 orders.

2 - Mutating nested props

Sometimes it might be tempting to edit a property in a prop that is an object or an array, because it’s “Easy” to do so. But is it the best thing to do ? Let’s look at an example

<template>
  <div class="hello">
    <div>Name: {{product.name}}</div>
    <div>Price: {{product.price}}</div>
    <div>Stock: {{product.stock}}</div>
 
    <button @click="addToCart" :disabled="product.stock <= 0">Add to card</button>
  </div>
</template>

export default {
  name: "HelloWorld",
  props: {
    product: {
      type: Object,
      default: () => ({})
    }
  },
  methods: {
    addToCart() {
      if (this.product.stock > 0) {
        this.$emit("add-to-cart");
        this.product.stock--;
      }
    }
  }
};

We have a Product.vue component which displays the product name, price and stock. It also contains a button to add the product to the cart. When clicking the button, it might be tempting to directly decrease the product.stock property. It’s easy to do so. However this can create couple of issues:

  • We mutate the prop without letting the parent now about it
  • We might get unexpected behavior or even worse, strange bugs because of this.
  • We introduce some logic in the product component which probably shouldn’t be there

Let’s assume a hypothetical case when another dev look over the code for the first time and sees the parent component.

<template>
   <Product :product="product" @add-to-cart="addProductToCart(product)"></Product>
</template>

import Product from "./components/Product";
export default {
  name: "App",
  components: {
    Product
  },
  data() {
    return {
      product: {
        name: "Laptop",
        price: 1250,
        stock: 2
      }
    };
  },
  methods: {
    addProductToCart(product) {
      if (product.stock > 0) {
        product.stock--;
      }
    }
  }
};

The dev might be tempted to think. Well, I should decrease the stock inside the addProductToCartmethod. By doing so, we introduce a small bug.

Now if we press the button, the quantity decreases by 2 instead of 1.

Imagine this is a special case, where such a check is made for special products/discounts and this code gets into a production environment. We might end up with users buying 2 products instead of 1.

If this doesn’t convince you, let’s assume another scenario. Let’s take the case of a user form for example. We pass in the user as a prop and want to edit its email and name. The code below might seem “right”

// Parent
<template>
  <div>
    <span> Email {{user.email}}</span>
    <span> Name {{user.name}}</span>
    <user-form :user="user" @submit="updateUser"/>
  </div>
</template>

import UserForm from "./UserForm"
export default {
  components: {UserForm},
  data() {
   return {
     user: {
      email: '[email protected]',
      name: 'Lorem Ipsum'
     }
   }
  },
  methods: {
    updateUser() {
     // Send a request to the server and save the user
    }
  }
}

// UserForm.vue Child
<template>
 <div>
  <input placeholder="Email" type="email" v-model="user.email"/>
  <input placeholder="Name" v-model="user.name"/>
  <button @click="$emit('submit')">Save</button>
 </div>
</template>

export default {
 props: {
   user: {
    type: Object,
    default: () => ({})
   }
 }
 }

It’s easy to add v-model on the user. Vue allows that. So why not do it?

  • What if we have a requirement to add a Cancel button and revert typed changes
  • What if our server call fails. How do we revert the changes on the user ?
  • Do we really want to show the changed email and name in the parent component before saving these changes ?

An easy “fix” might be to simply clone the user before sending it as a prop

<user-form :user="{...user}">

While this might work, it’s only a work around for the real problem. Our UserForm should have its own local state. Here’s what we can do.

<template>
  <div>
   <input placeholder="Email" type="email" v-model="form.email"/>
   <input placeholder="Name" v-model="form.name"/>
   <button @click="onSave">Save</button>
   <button @click="onCancel">Save</button>
  </div>
</template>

export default {
 props: {
   user: {
    type: Object,
    default: () => ({})
   }
 },
 data() {
  return {
   form: {}
  }
 },
 methods: {
  onSave() {
   this.$emit('submit', this.form)
  },
  onCancel() {
   this.form = {...this.user}
   this.$emit('cancel')
  }
 }
 watch: {
   user: {
    immediate: true,
    handler: function(userFromProps){
     if(userFromProps){
       this.form = {
         ...this.form,
         ...userFromProps
       }
     }
    }
   }
 }
 }

While the code above definitely feels more verbose, it’s better and avoids the issues described above. We watch for the user prop changes and then copy it to our own local form inside data. This allows us to have an individual state for the form and:

  • Decide to cancel the changes by re-assigning the form this.form = {...this.user}
  • Have isolated state for the form
  • Not affect the parent unless we want to
  • Have control when we Save the changes
3 - Directly accessing parent components

Accessing and doing operations on other components other than the component itself can lead to inconsistencies, bugs, strange behaviors and coupled components.

We’ll take a very simple case of a dropdown component. Let’s assume we have a **dropdown **(parent) and **dropdown-menu **(child). When the user clicks a certain option, we’d like to close the **dropdown-menu **which is shown/hidden from the parent **dropdown. **Let’s see an example

// Dropdown.vue (parent)
 
<template>
  <div>
    <button @click="showMenu = !showMenu">Click me</button>
    <dropdown-menu v-if="showMenu" :items="items"></dropdown-menu>
  </div>
<template>

export default {
 props: {
  items: Array
 },
 data() {
  return {
    selectedOption: null,
    showMenu: false
  }
 }
 }

// DropdownMenu.vue (child)
<template>
 <ul>
   <li v-for="item in items" @click="selectOption(item)">{{item.name}}</li>
 </ul>
<template>

export default {
 props: {
  items: Array
 },
 methods: {
   selectOption(item) {
    this.$parent.selectedOption = item
    this.$parent.showMenu = false
   }
 }
}

Pay attention to selectOption method. Although this is very rare, some people would be tempted to access the $parent directly because it’s easy.

The code would work fine at first sight but what if:

  • We change the showMenu or selectedOption property. The dropdown will fail to close and no option will be selected
  • We want to add a transition to the dropdown-menu
// Dropdown.vue (parent)
<template>
  <div>
    <button @click="showMenu = !showMenu">Click me</button>
    <transition name="fade">
      <dropdown-menu v-if="showMenu" :items="items"></dropdown-menu>
    </dropdown-menu>
  </div>
<template>

Again the code will fail because the $parent changed. The parent of dropdown-menu is no longer the dropdown component but the transition component.

**Props down, events up **is the right way. Here’s our example from above, modified to use events

// Dropdown.vue (parent)
<template>
  <div>
    <button @click="showMenu = !showMenu">Click me</button>
    <dropdown-menu v-if="showMenu" :items="items" @select-option="onOptionSelected"></dropdown-menu>
  </div>
<template>

export default {
 props: {
  items: Array
 },
 data() {
  return {
    selectedOption: null,
    showMenu: false
  }
 },
 methods: {
   onOptionSelected(option) {
     this.selectedOption = option
     this.showMenu = true
   }
 }
 }

// DropdownMenu.vue (child)
<template>
 <ul>
   <li v-for="item in items" @click="selectOption(item)">{{item.name}}</li>
 </ul>
</template>

export default {
  props: {
   items: Array
  },
  methods: {
    selectOption(item) {
     this.$emit('select-option', item)
    }
  }
}

By using events we are no longer coupled to the parent component. We are free to change the data properties inside the parent component, add transitions and not think about how our code might affect the parent component. We simply notify the parent that an action happened. It's up to the **Dropdown **how to handle the option selection and close the menu.

Conclusion

The shortest code is not always the best and "easy and fast" ways can often have disadvantages. Every programming language, project or framework requires patience and time to use it right. The same applies for Vue. Write your code carefully and with patience.

What are the differences between the various JavaScript frameworks? E.g. Vue.js, Angular.js, React.js

What are the differences? Do they each have specific use contexts?

What are the differences? Do they each have specific use contexts?

Ember.js vs Vue.js - Which is JavaScript Framework Works Better for You

Ember.js vs Vue.js - Which is JavaScript Framework Works Better for You

In this article we will discuss full details and comparison of both Ember.js and Vue.js

JavaScript was initially created to work for web applications. But today they have become the favorite of mobile app developers. Most of the developers prefer to work with frameworks based on JavaScript. It simplifies coding. You can use JavaScript with almost any framework.

The use of a particular framework will decide how easy and fast it is to create the app. So, you must choose the best one suited for the app that you are planning to build. You must make a wise choice so that you benefit in the end. Among the crowded market, two of the frameworks stand out. We will make a comparison between Ember.js and Vue.js.

Why Do You Select A Particular Framework?

Before we start comparing the two frameworks, we should understand the factors that lead to the choice of a framework. Each developer chooses a framework before he or she goes to work on an app. Let us see the reasons for the selection.

● The codes must be easy to understand and transparent.

● The framework should give the maximum power with the least amount of coding.

● The framework should provide a well laid out structure to work on.

● Does the framework support an in-built router or an external plug-in router?

● The framework should be able to transfer more data on a full page-load so that it becomes a single-page app. A single-page app is more beneficial for the application.

● In single page architectures if there is a need for users to share links to sub-screens within the interface, then the framework should have the capacity to route based on the URL.

● A tighter template option can help in enabling two-way binding.

● The framework should not conflict any third-party library.

● Testing the codes inside the framework should be easy.

● The framework should provide the HTTP client service for AJAX calls

● The documentation is essential. It should be complete and up-to-date.

● The framework should be compatible with the latest version of the browser.

● The framework has to fulfill the above conditions for easy construction of the app. You must ensure that the framework you choose meets the conditions.

Vue.js Explained

Developers are always looking at new frameworks to build their apps. The main requirements are speed and low cost. The framework should be easy to use by even new developers. You should be able to use it at low cost. Other considerations are about simple coding, proper documentation, etc.

Vue.js combines a lot of good when it comes to software language for web app development. The architecture of Vue.js is easy to put in use. The apps developed using Vue.js are easy to integrate with new apps.

Vue.js is a very lightweight framework. It makes it fast to download. It is also much faster than other frameworks. The single-file component nature of the framework is also beneficial. The size has made it very popular.

You can further decrease weight. With Vue.js you can separate the template-to-virtual DOM and compiler. You can only deploy the minified and zipped interpreter which is only 12 KB. You can compile the templates in your machine.

Another significant advantage of Vue.js is that it can integrate easily with existing applications created with JavaScript. It will make it easy for using this framework to make changes to applications already present.

Vue.js also integrates easily with other front-end libraries. You can plug in another library and make up for any deficiency in this framework. This feature makes this tool a versatile one.

Vue.js uses the method of rendering on the streaming-side server. You can render your component and get a readable stream. You can then send this to the HTTP server. It makes the server highly responsive. Your users will get the rendered content very quickly.

Vue.js is very SEO friendly. As the framework supports server-side rendering, the views are rendered directly on the server. The search engines list these.

But the most important thing for you is the ease with which you can learn Vue.js. The structure is elementary. Even new developers will find it easy to use it to build their apps. This framework helps in developing both small and large templates. It helps to save a lot of time.

You can go back and check your errors very easily. You can travel back and inspect all the states apart from testing your components. It is another important feature as far as any developer is concerned.

Vue.js also has very detailed documentation. It helps in writing your applications very quickly. You can build a web page or app with the basic knowledge of HTML or JavaScript.

● Vue.js has pure architecture. It helps in integration with other apps

● Vue.js is lightweight and fast. It can be made lighter by deploying only the interpreter

● You can separate the compiler and the template-to-virtual DOM.

● Due to smooth integration, you can use this to make changes to existing apps

● To make up for any shortfall, you can plug-in any library and makeup.

● As Vue.js uses streaming-side server rendering, your users can get quick responses.

● The server-side rendering also helps in being ranked higher by search engines.

● It has a simple structure. Easy to use for any new developer

● You can go back and check and correct your errors.

● You can check all the existing states.

● Detail documentation also helps build the web page or application very quickly.

Ember.js Decoded

Ember.js is an MVVM model framework. It is open-source software. This platform is mostly used for creating complex multi-page applications. It maintains up-to-date features without discarding any of the old features.

With this framework, you have to follow the architecture of the framework strictly. The JS framework is very tightly organized. It reduces the flexibility that other frameworks might offer.

There is a very refined and developed control system for its platforms and tools. You can integrate it with the new version with the tools provided. There is strict guidance about avoiding outdated APIs.

You can understand Ember’s APIs easily. They are also easy to work. You can make use of highly complex functionalities simply and straightforwardly.

The performance is better as similar jobs are processed together. It creates batches of similar bindings and DOM updates to improve the performance. It means that the browser needs to process them in one go. It will avoid recomputing for each task, wasting a lot of time.

You can write the codes in a simple manner and modules. You can use any of Ember’s APIs. It is possible due to the presence of Promises everywhere.

Ember comes with a well-written guide. The API is recorded in a useful manner. It is a front-end framework that is loaded. Ember has a router, pipeline, services, etc. of its own.

The basis for views, controllers, models, and framework is the Ember Object Model. All components come from the same objects. The framework is firm and steady. The reason is that all elements have similar jobs and characteristics.

Ember has made the general application, organization, and structure clear so that you don’t make any mistakes. You will have no chance to complicate the application unnecessarily. If you have to go out of the defined limits, you will have to force your way out.

The language used for templating in Embers is Handlebars. This language helps Embers to keep its logic out of view. The clean syntax of Handlebars makes it easy for you to read and understand the templates. Handlebar templates are faster to load.

Another advantage you gain from Handlebar is that you don’t have to update your template every time you add or remove data from the page. It will be done automatically by the language itself.

A community that is continually improving the framework supports Ember. They are updating the framework with the latest technology. They also make sure that backward compatibility is possible.

● Ember.js is an open-source MVVM model framework suitable for complex multiple-page applications.

● It offers both the latest and old features.

● It has a very tightly structured framework which doesn’t offer much flexibility

● A very refined control system helps you to integrate with new versions without any problem.

● There is strict guidance about avoiding outdated API versions.

● Ember’s APIs help you to use complex functionalities in a simple manner

● There is no recomputing for each task as the framework allows the browser to do similar functions together.

● Promises allow you to write modular and straightforward code using any API of Ember.js.

● Ember.js is a fully loaded, front-end framework.

● The framework is stable because all components have the same functionalities and properties.

● It has well-defined limitations which will prevent your complicating your application

● Handlebars, the language used by Ember.js allows you to read and understand templates easily. It also helps to load the templates faster.

● Handlebars will ensure to update the template every time you add or remove data.

● Ember.js has an active community that updates the framework regularly and facilitates backward compatibility.

A Comparison Between Ember.js And Vue.js

This article intends to compare the features of both frameworks. Let us see how the characteristics of these frameworks compare. It will help you to make use of the right framework for your web application.

When you need a modern engine for an old application, it is Vue.js which will help you. It combines the best properties of other frameworks. Vue.js is a developing framework. A ready-to-use library of interface elements does not exist. However, many third-party libraries can help you.

Ember.js offers you a well-organized and trustworthy framework. When the development team is big, this is the framework that suits best. It allows everyone to understand the written code and contribute to a common project. The technology will be up-to-date, and the platform will be stable.

Vue.js can help you use the syntax of different kinds. It helps in writing the codes with ease. It is also an SEO friendly framework. Ember is a fully loaded front-end framework and can help you develop the applications very fast. But it is not suitable for developing small projects.

It is not easy to say this is better than that. It will depend on what kind of project you have undertaken. Both have their pluses and minuses. The below table will help in a better comparison.

Final Thoughts

It is not easy to conclude as to which is better. It all depends on the application that you want to develop. Both frameworks are developing. Both are getting updates. Both the communities are working on the frameworks.

While Vue.js is more comfortable for writing codes, Ember is a full-stack framework allowing the development of apps very fast. It is suitable for big projects. It is too complicated to be used for smaller projects.

We hope you had a great time reading this article. If you’ve any questions or suggestions related to this blog, then feel free to ask them in the comment section. Thank You.!