Extract a number from a string using JavaScript
In this article, we will learn how we can extract the numbers if exist in a given string. we will have a string and we need to print the numbers that are present in the given string in the console.
These are the following methods by using these we can solve the problems:
Table of Content
- JavaScript reduce() method with the spread operator to extract a number from a string
- JavaScript replace() method with regEx to extract a number from a string
- JavaScript for loop to extract a number from a string
- Using Array.prototype.filter with split
JavaScript match method with regEx to extract a number from a string
The number from a string in javascript can be extracted into an array of numbers by using the match method. This function takes a regular expression as an argument and extracts the number from the string. The regular expression for extracting a number is (/(\d+)/).
Example 1: This example uses the match() function to extract numbers from strings with regular expressions.
// Function to extract numbers
function myBeginner() {
// Input string
let str = "jhkj7682834";
console.log(str)
// Using match with regEx
let matches = str.match(/(\d+)/);
// Display output if number extracted
if (matches) {
console.log(matches[0]);
}
}
// Function call
myBeginner();
Output
jhkj7682834 7682834
Example 2: This example uses the match() function to extract numbers from strings.
// Function to extract numbers
function myBeginner() {
// Input string
let str = "foo35bar5jhkj88";
console.log(str)
// Using match with regEx
let matches = str.match(/\d+/g);
// Display output if number extracted
if (matches) {
console.log(matches[0] +', '+ matches[1]+', ' + matches[2]);
}
}
// Function call
myBeginner();
Output
foo35bar5jhkj88 35, 5, 88
JavaScript reduce() method with the spread operator to extract a number from a string
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: This example spread operator to convert into an array and the reduce method to extract all the numbers from the string.
// Function to extract numbers
function myBeginner() {
// Input string
let str = "jhkj7682834";
let c = "0123456789";
console.log(str);
function check(x) {
return c.includes(x) ? true : false;
}
let matches = [...str].reduce(
(x, y) => (check(y) ? x + y : x),"");
// Display output if number extracted
if (matches) {
console.log(matches);
}
}
// Function call
myBeginner();
Output
jhkj7682834 7682834
JavaScript replace() method with regEx to extract a number from a string
The string.replace() is an inbuilt method in JavaScript that is used to replace a part of the given string with another string or a regular expression. The original string will remain unchanged.
Example: In this example, we will use the JavaScript replace() method with regEx to extract the numbers out of given string
// Function to extract numbers
function myBeginner() {
// Input string
let str = "jhkj7682834";
console.log(str);
// Using match with regEx
let matches = str.replace(/[^0-9]/g, "");
// Display output if number extracted
if (matches) {
console.log(matches);
}
}
// Function call
myBeginner();
Output
jhkj7682834 7682834
JavaScript for loop to extract a number from a string
This approach loops through each character in the string and checks if it’s a number using isNaN(). If the character is a number, it appends it to numberStr.
Example: This example use for loop to extract all numbers present in the string.
function extractNumbers(str) {
let numbers = "";
for (let i = 0; i < str.length; i++) {
if (!isNaN(str[i])) {
numbers += str[i];
}
}
console.log(numbers)
}
// Input string
let str = "jhkj7682834hhdg237";
console.log(str);
extractNumbers(str);
Output
jhkj7682834hhdg237 7682834237
Using Array.prototype.filter with split
Using Array.prototype.filter with split, you can extract numbers from a string by splitting the string into an array of characters, filtering out non-numeric characters, and joining the remaining characters back into a string.
Example:
let str = "The price is 123 dollars";
let number = str.split('').filter(char => !isNaN(char) && char !== ' ').join('');
console.log(number); // "123"
Output
123
JavaScript is best known for web page development but it is also used in a variety of non-browser environments. You can learn JavaScript from the ground up by following this JavaScript Tutorial and JavaScript Examples.
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