Index inside map() function

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9 Answers

indexfunctioninside
90%

In JavaScript, map() method handles array elements, which creates a new array with the help of results obtained from calling function for each and every array element in an array. The index is used inside map() method to state the position of each element in an array, but it doesn’t change the original array.,arrayobj: The arrayobj is an optional argument in map() which is the array object where the current element belongs.,index: The index is an optional argument map() which is an array index of provided current element.,Parameters: The Index inside function accepts three parameters as mentioned above and described below:

Syntax:

array.map(function(currentelement, index, arrayobj) {

   // Returns the new value instead of the item

});

Output:

welcome
0
to
1
GeeksforGeeeks
2
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88%

One can access the index Array.prototype.map() via the second argument of the callback function. Here is an example:,The third argument of the callback function exposes the array on which map was called upon,callback - Function that produces an element of the new Array, taking three arguments:,Software Recommendations

Example:

const list = ['h', 'e', 'l', 'l', 'o'];
list.map((currElement, index) => {
   console.log("The current iteration is: " + index);
   console.log("The current element is: " + currElement);
   console.log("\n");
   return currElement; //equivalent to list[index]
});

Output:

The current iteration is: 0 <br>The current element is: h

The current iteration is: 1 <br>The current element is: e

The current iteration is: 2 <br>The current element is: l

The current iteration is: 3 <br>The current element is: l

The current iteration is: 4 <br>The current element is: o
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To find an index of the current iterable inside the JavaScript map() function, you have to use the callback function’s second parameter. An index used inside the JavaScript map() method is to state the position of each item in an array, but it doesn’t modify the original array.,JavaScript map() function returns a new array, with each item being the result of the callback function.,To access the index of the array map() method, use the second argument of the callback function. The array map() method creates the new array populated with the results of calling the provided function on every item in the calling array.,Remember that you have to use the regular function keyword to declare the callback since an arrow function doesn’t have its binding to this keyword.

Syntax

array.map(function(currentItem, index, arrayobj), thisValue)
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The map() method creates a new array populated with the results of calling a provided function on every element in the calling array. ,A new array with each element being the result of the callback function.,The callbackFn function accepts the following arguments:, One alternative output of the map method being called with parseInt as a parameter runs as follows:

// Arrow function
map((element) => {
   ...
})
map((element, index) => {
   ...
})
map((element, index, array) => {
   ...
})

// Callback function
map(callbackFn)
map(callbackFn, thisArg)

// Inline callback function
map(function callbackFn(element) {
   ...
})
map(function callbackFn(element, index) {
   ...
})
map(function callbackFn(element, index, array) {
   ...
})
map(function callbackFn(element, index, array) {
   ...
}, thisArg)
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75%

To access the index of the array map() method, use the second argument of the callback function. JavaScript array map() method creates the new array populated with the results of calling the provided function on every item in the calling array.,To find index of the current iterable inside the JavaScript map() function, you have to use the callback function’s second parameter. An index used inside the JavaScript  map() method is to state the position of each item in an array, but it doesn’t modify the original array.,Today almost all websites are using it as web technology, mind is that there is maximum scope in JavaScript in the coming time, so if you want to become a programmer, then you can be very beneficial to learn JavaScript.,It is said that a digital resource a business has must be interactive in nature, so the website or the business app should be interactive. How do you make the app interactive? With the use of JavaScript.

Syntax

array.map(function(currentItem, index, arrayobj), thisValue)
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Search Answer Titles

function listFruits() {
   let fruits = ["apple", "cherry", "pear"]

   fruits.map((fruit, index) => {
      console.log(index, fruit)
   })
}

listFruits()

// https://jsfiddle.net/tmoreland/16qfpkgb/3/
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The map() method calls the provided function once for each element in an array, in order.,The map() method creates a new array with the results of calling a function for every array element.,map() does not execute the function for empty elements.,Get the full name for each person in the array:

Definition and Usage

The map() method creates a new array with the results of calling a function for every array element.

map()
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The syntax of the map() method is straightforward. The method accepts a callback function, which takes the currentValue, index, and the return array as arguments, providing a new array as output:,array.map(callback function (currentValue, index, array), this.Arg),When comparing map() versus forEach(), filter(), and reduce(), it is important to note that while all of these methods iterate through an array, they differ in their return value:,map() returns a new array with the same length as the parent array.

For example, the following code iterates through an array of numbers and multiplies each number by 2:

const numArray = [6, 7, 15, 22, 45];
const numArrayMult = numArray.map(num => num * 2);
console.log(numArrayMult); //Output: [12, 14, 30, 44, 90]
console.log(numArray); //Output: [6, 7, 15, 22, 45]
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index: the index of the current element being processed., index: the index of the current element being processed. ,arr: the array object on which map() is called., arr: the array object on which map() is called.

//creating an array
var my_array = [1, 3, 5, 2, 4];

//map calls a function which has "item" passed as parameter
//map will pass each element of my_array as "item" in this function
//the function will double each element passed to it and return it
result = my_array.map(function(item) {
   return item * 2;
});

//prints new list containing the doubled values
console.log(result);
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