JavaScript String startsWith()
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
searchStringis the characters to be searched for at the start of this string.positionis an optional parameter that determines the start position to search for thesearchString. 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.