How to convert array of strings to array of numbers in JavaScript ?

Converting an array of strings to an array of numbers in JavaScript involves transforming each string element into a numerical value. This process ensures that string representations of numbers become usable for mathematical operations, improving data handling and computational accuracy in applications.

Input: ["1","2","3","4","5"]
Output: [1,2,3,4,5]

Input: ["10","21","3","14","53"]
Output: [10,21,3,14,53]

There are two methods to do this, which are given below:

Array traversal and typecasting

In this method, we traverse an array of strings and add it to a new array of numbers by typecasting it to an integer using the parseInt() function.

Example: In this example, we converts an array of strings into an array of numbers using the parseInt() function within a loop. It pushes each converted integer into a new array and then prints it.

// Create an array of string
let stringArray = ["1", "2", "3", "4", "5"];

// Create an empty array of number
let numberArray = [];

// Store length of array of string
// in letiable length
length = stringArray.length;

// Iterate through array of string using
// for loop
// push all elements of array of string
// in array of numbers by typecasting
// them to integers using parseInt function
for (let i = 0; i < length; i++)

    // Instead of parseInt(), Number()
    // can also be used
    numberArray.push(parseInt(stringArray[i]));

// Print the array of numbers
console.log(numberArray);

[ 1, 2, 3, 4, 5 ]

Using map() method of JavaScript

Javascript map() method creates an array by calling a specific function on each element present in the parent array. It is a non-mutating method. Generally, the map() method is used to iterate over an array and call function on every element of the array. 

Example: In this example, we converts an array of strings into an array of numbers using the map() function, which applies the Number constructor to each element, then prints the resulting array of numbers.

// Create an array of string
let stringArray = ["10", "21", "3", "14", "53"];

// Create a numberArray and using
// map function iterate over it
// and push it by typecasting into
// int using Number
let numberArray = stringArray.map(Number);

// Print the array of numbers
console.log(numberArray);

[ 10, 21, 3, 14, 53 ]

Using forEach loop of JavaScript

The arr.forEach() method calls the provided function once for each element of the array. The provided function may perform any kind of operation on the elements of the given array. 

Example: In this example, we converts an array of strings into numbers using the forEach() loop. It iterates over each string, typecasts it into a number using the + operator, and then prints the array.

// Create an array of string
let stringArray = ["10", "21", "3", "14", "53"];

// Create a numberArray and using
// forEach loop iterate over it
// and push it to numberArray with typecasting it into
// int using + operator
let numberArray = [];
stringArray.forEach( ele => numberArray.push(+ele))

// Print the array of numbers
console.log(numberArray);

[ 10, 21, 3, 14, 53 ]

Using reduce method of JavaScript

The Javascript arr.reduce() method in JavaScript is used to reduce the array to a single value and executes a provided function for each value of the array (from left to right) and the return value of the function is stored in an accumulator. 

Example: In this example, we converts an array of strings into numbers using the reduce() function. It iterates through each string, typecasts it using the + operator, stores the results in an array, and prints it.

// Create an array of string
let stringArray = ["10", "21", "3", "14", "53"];

// Create a numberArray and using
// reduce function iterate over it
// and push it to numberArray with typecasting it into
// int using + operator
let numberArray = stringArray.reduce( (acc, x ) => acc.concat(+x), [])

// Print the array of numbers
console.log(numberArray);

[ 10, 21, 3, 14, 53 ]

Using a for loop

To convert an array of strings to numbers using a for loop, iterate through each string, convert it to a number using Number(), and push it to a new array. This method provides control and flexibility for handling each element individually.

Example: In this example we converts an array of strings into an array of numbers using a for loop. It iterates through each string, converts it to a number using Number(), and then prints the result.

const stringArray = ["1", "2", "3", "4", "5"];
const numberArray = [];
for (let i = 0; i < stringArray.length; i++) {
  numberArray.push(Number(stringArray[i]));
}
console.log(numberArray); 

[ 1, 2, 3, 4, 5 ]