JavaScript String startsWith()

Summary: in this tutorial, you will learn how to use the JavaScript String startsWith() method to check if a string starts with a substring.

Introduction to the JavaScript startsWith() method

The startsWith() returns true if a string starts with a substring or false otherwise.

The following shows the syntax of the startsWith() method:

String.startsWith(searchString [,position])Code language: CSS (css)

Arguments

• searchString is the characters to be searched for at the start of this string.
• position is an optional parameter that determines the start position to search for the searchString. It defaults to 0.

JavaScript String startsWith() examples

Suppose that you have a string called title as follows:

const title = 'Jack and Jill Went Up the Hill';Code language: JavaScript (javascript)

The following example uses the startsWith() method to check if the title starts with the string 'Jack':

console.log(title.startsWith('Jack'));Code language: JavaScript (javascript)

Output:

trueCode language: JavaScript (javascript)

The startsWith() method matches characters case-sensitively, so the following statement returns false:

title.startsWith('jack');Code language: JavaScript (javascript)

This example uses the startsWith() method with the second parameter that determines the beginning position to start searching:

console.log(title.startsWith('Jill', 9));Code language: JavaScript (javascript)

Output:

trueCode language: JavaScript (javascript)

Put it all together:

const title = 'Jack and Jill Went Up the Hill';

console.log(title.startsWith('Jack'));
console.log(title.startsWith('jack'));
console.log(title.startsWith('Jill', 9));
Code language: JavaScript (javascript)

Output:

true
false
trueCode language: JavaScript (javascript)

Summary

• Use the String startsWith() method to check if a string starts with a substring.