Javascript Array Keys Example | Array Keys In Javascript

Javascript array keys() method returns the new Array Iterator object that contains the keys for each index in an array. The array keys() method does not change the original array.

Javascript Array Keys Example

The syntax for the Javascript Array keys() method is the following.

arr.keys()

Let us take a simple example.

// app.js

let arr = ['a', 'b', 'c'];
let iteratorObj = arr.keys();

console.log(iteratorObj);

So, it has given us iteratorObj. We can get the values by iterating for…of() loop.

// app.js

let arr = ['a', 'b', 'c'];
let iterator = arr.keys();

console.log(iterator);

for (let key of iterator) {
  console.log(key);
}

#javascript #javascript array keys #js

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Javascript Array Keys Example | Array Keys In Javascript

Javascript Array Keys Example | Array Keys In Javascript

Javascript array keys() method returns the new Array Iterator object that contains the keys for each index in an array. The array keys() method does not change the original array.

Javascript Array Keys Example

The syntax for the Javascript Array keys() method is the following.

arr.keys()

Let us take a simple example.

// app.js

let arr = ['a', 'b', 'c'];
let iteratorObj = arr.keys();

console.log(iteratorObj);

So, it has given us iteratorObj. We can get the values by iterating for…of() loop.

// app.js

let arr = ['a', 'b', 'c'];
let iterator = arr.keys();

console.log(iterator);

for (let key of iterator) {
  console.log(key);
}

#javascript #javascript array keys #js

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

Javascript Array From Example | Array.prototype.from()

Javascript array from() is an inbuilt function that creates a new, shallow-copied array instance from an array-like object or iterable object.

The Array .from() lets you develop Arrays from the array-like objects (objects with a length property and indexed items) or  iterable objects ( objects where you can get its items, such as Map and  Set).

The Array from() function was introduced in ECMAScript 2015.

Javascript Array From Example

Array.from() method in Javascript is used to creates a new  array instance from a given array. If you pass a  string to the Array.from() function, then, in that case, every alphabet of the string is converted to an element of the new array instance. In the case of integer values, a new array instance simply takes the elements of the given Array.

The syntax of the Array.from() method is the following.

Syntax

Array.from(arrayLike[, mapFn[, thisArg]])

#javascript #ecmascript #javascript array from #array.prototype.from

Javascript Array Shift Example | Array.prototype.shift()

Javascript array shift() is an inbuilt function that removes the first item from an array and returns that deleted item. The shift() method changes the length of the array on which we are calling the shift() method. Javascript Array Shift method is not  pure function as it directly modifies the  array.

Javascript Array Shift Example

Javascript shift() method removes the item at the zeroeth index and shifts the values at consecutive indexes down, then returns that removed value.

If we want to remove the last item of an array, use the  Javascript pop() method.

If the length property is 0,  undefined is returned.

The syntax for shift() method is the following.

array.shift()

An array element can be a  string, a number, an  array, a boolean, or any other  object types that are allowed in the Javascript array. Let us take a simple example.

#javascript #array.prototype.shift #javascript pop #javascript shift