JavaScript Array find | Find First Occurrence of Array

In this tutorial, you will learn JavaScript find() method and how to search the first occurrence element in an array using this javascript array method.

If you will use indexOf() or lastIndexOf() method to find the value in an array, These methods only allow you to find one value at a time in a javascript array.
You can use the new method find() to find first occurrence of an element in an array. Instead of these indexOf() or lastIndexOf() method. Because in es6 enhance the capability to finding the elements in the javascript array

Syntax of the find() method

The following syntax demonstration of the find() method:

find(callback(element[, index[, array]])[, thisArg])

Parameters

The find() takes two parameters:

  • The first one is the callback function and it’s optional.
  • The second one is used as this inside the callback.

1) callback

The callback is a function to execute on each element of the array. It accepts 3 parameters:

  • element is the current element of an array.
  • index the index of the current element of an array.
  • array the array that the find() was called upon.

2) thisArg

is the object to use as this inside the callback.

Return value

For each element of an array, The find() executes the callback function until the callback returns a truthy value.  In this case, the find() immediately returns the value of that element. Otherwise, it returns undefined.

Note that, JS find() method is truly different from the findIndex() method. The findIndex() method is used to search the position of an element in an array.

Examples: JavaScript find()

Suppose you have a numeric array and want to search the first odd number in it, you can use these find() method for these.

See the following example:

let numbers = [1, 2, 3, 4, 5];

console.log(numbers.find(e => e % 2 == 1));

Output:

1

If you want to find first even number in an array, you can find the following:

let numbers = [1, 2, 3, 4, 5];

console.log(numbers.find(e => e % 2 == 0));

Output:

2

Suppose that you have a list of computers objects with name and price properties as follows:

let computers = [{
    name: 'Dell',
    price: 60000
}, {
    name: 'HP',
    price: 50000
}, {
    name: 'Apple',
    price: 80000
}];

The following javascript code uses the find() method to find the first computer whose price is greater than $ 60000.

let computers = [{
    name: 'Dell',
    price: 60000
}, {
    name: 'HP',
    price: 50000
}, {
    name: 'Apple',
    price: 80000
}];
console.log(computers.find(c => c.price > 60000));

Output:

{name: "Apple", price: 80000}

Conclusion

In this tutorial, you have learned how to use the JavaScript Array’s find() method and using this method how to find the first occurrence of an element in an array.

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JavaScript Array find | Find First Occurrence of Array
Coy  Roberts

Coy Roberts

1600481520

Javascript array find: How to Find Element in Javascript

Javascript array find() is an inbuilt js function that returns the value of the first item in the Array that satisfies a provided testing function. Otherwise,  undefined will be returned. The array find() method returns the value of the first element in an array that passes a test of provided function.

If an Array find() method finds an item where the function returns a true value. Javascript find() returns the value of that array item immediately and does not check the remaining values of that Array.

Javascript array find

Javascript Array.find() is the inbuilt function that is used to get a value of the first item in the Array that meets the provided condition. If you need an index of the found item in the Array, use the  findIndex(). If you need to find an index of the value, use Array  .prototype.indexOf(). If you need to find if the value exists in an array, use Array  .prototype.includes().

It checks all the items of the Array, and whichever the first item meets, the condition is going to print. If more than one item meets the condition, then the first item satisfying the requirement is returned. Suppose that you want to find the first odd number in the Array. The argument function checks whether an argument passed to it is an odd number or not.

Javascript find() function calls an argument function for every item of the Array.  The first odd number for which argument function returns true is reported by the find() function as the answer.

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Lowa Alice

Lowa Alice

1624388400

JavaScript Arrays Tutorial. DO NOT MISS!!!

Learn JavaScript Arrays

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#arrays #javascript #javascript arrays #javascript arrays tutorial

Terry  Tremblay

Terry Tremblay

1602154740

Fill and Filter in Array in JavaScript

By the word Array methods, I mean the inbuilt array functions, which might be helpful for us in so many ways. So why not just explore and make use of them, to boost our productivity.

Let’s see them together one by one with some amazing examples.

Array.fill():

The _fill()_ method changes all elements in an array to a static value, from a start index (default _0_) to an end index (default _array.length_). It returns the modified array.

In simple words, it’s gonna fill the elements of the array with whatever sets of params, you pass in it. Mostly we pass three params, each param stands with some meaning. The first param value: what value you want to fill, second value: start range of index(inclusive), and third value: end range of index(exclusive). Imagine you are going to apply this method on some date, so that how its gonna look like eg: array.fill(‘Some date’, start date, end date).

NOTE: Start range is inclusive and end range is exclusive.

Let’s understand this in the below example-

//declare array
var testArray = [2,4,6,8,10,12,14];

console.log(testArray.fill("A"));

When you run this code, you gonna see all the elements of testArray will be replaced by 'A' like [“A”,"A","A","A","A","A","A"].

#javascript-tips #array-methods #javascript-development #javascript #arrays

Ollie  Dietrich

Ollie Dietrich

1625988600

JavaScript Array Methods #4: Array .find() Method

The Javascript Array .find() method is used to get the value of the first element in the array that satisfies the provided condition in a callback function. It checks all the elements of the array and whichever first element satisfies the condition is going to print.

The function and syntax of find() are very much like the Array .filter() method, except it, only returns a single element. Another difference is when nothing is found, this method returns a value of undefined.

Syntax:
array.find(function(currentValue, index, arr), thisValue)

▶ #1: Array .map() Method | JavaScript Array Methods
https://www.youtube.com/watch?v=oystIFwyt4o

▶ #2: Array .forEach() Method | JavaScript Array Methods
https://www.youtube.com/watch?v=e2qbolkHKt4

▶ #3: Array .filter() Method | JavaScript Array Methods
https://www.youtube.com/watch?v=nN1k3HeG2oc

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Cayla  Erdman

Cayla Erdman

1597470780

A quick guide to JavaScript Arrays

Introduction

Arrays are a structure common to all programming languages so knowing what they are and having a firm grasp on what you’re able to accomplish with Arrays will take you a long way in your journey as a software developer. The code examples I share in this post will be in JavaScript but the concepts are common among all languages. What you learn here can easily be translated to any other language you work with.

In this post I’ll be covering how to perform the create, read update and delete operations using arrays, some common functions that come with the Array prototype and also how to implement them.


What is an Array

Before we jump into the juicy bits of Arrays, lets quickly gloss over what they are. Arrays

  • are a fundamental data type in JavaScript
  • are an ordered collection of values called **elements **that are stored at and accessed via an index
  • are untyped, meaning that the elements of an array could be of different types. This allows us to create complex arrays such as an array of objects or even an array of arrays (multidimensional arrays)
  • can have elements that are constants or expressions
  • have a property called length that tells you the number of elements in the array
  • inherit properties from Array.prototype that includes a wide variety useful functions that can be called from arrays or array-like objects

CRUD operations using Arrays

If you’re not familiar with the term CRUD it stands for Create, Read, Update and Delete. In this section we’ll go through each one of these operations and cover different ways you can perform each one.

Creating Arrays

There are several ways you can create an Array but the most common ways are by using

  • the Array literal syntax
  • the Array constructor i.e. new Array()

Lets take a look at each one with examples

Array literal

The array literal is the most common way of creating an array. It uses the square brackets as a notion of a container followed by comma separated values inside the square brackets. The following examples show how to use the array literal syntax and how arrays are untyped i.e. can contain elements of different types.

Image for post

Examples of untyped arrays in JavaScript created with the array literal syntax.

Array constructor

Another way to create an array is through the Array constructor.

const myArray = new Array();

Using the Array constructor, as shown above, is the same as creating an array with the array literal syntax. i.e.

// The following two lines behave exactly the same way i.e. both create an empty arrays

const myArray = new Array();
const myOtherArray = [];

The array constructor, however, is able to receive arguments that allow it to behave in different ways depending on the number and type of arguments passed to it.

  • You can pass a single numeric argument which creates an array of the specified length. This option is mostly used when you know how many elements you’ll be placing in the array
const myArray = new Array(5);

Note: If you want to define the array with a specified size, as shown above, the argument passed must be a numeric value. Any other type would be considered as the first element that’ll be placed in the array.

  • Or you can pass two or more arguments or a non-numeric argument to place the values inside the array. This works the same way as shown in the array literal examples.

Image for post

Examples of arrays created by using the Array constructor in JavaScript

As stated earlier, these two ways are the most common ways of creating arrays that you’ll see and use 99% of the time. There are a few other ways but we won’t dive deep into how they work. They are

  • the spread operator const someArray = […someOtherArray]
  • the static method Array.of()
  • and the static method Array.from()

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