JavaScript String.startsWith() Method

1. Syntax of JavaScript string.startsWith():
2. Example Codes: Use the searchValue Parameter Value for the string.startsWith() Method
3. Example Codes: Use the position Parameter Value for the string.startsWith() Method
4. Example Codes: Use a Punctuation in the searchValue Parameter for the string.startsWith() Method

The startsWith() method takes the string and the position to find if the string starts with the searchValue. When the start position parameter is empty, the startsWith() method checks the index position 0.

Syntax of JavaScript string.startsWith():

referenceString.startsWith(searchValue);
referenceString.startsWith(searchValue,position);

Parameters

Return

It returns true when a string’s specific index position starts with the searchValue. Else, it returns false.

Example Codes: Use the searchValue Parameter Value for the string.startsWith() Method

The JavaScript startsWith() method uses the searchValue parameter to determine whether the string starts with a specified character or a regular expression.

In the example below, we didn’t pass the position parameter. The string.startsWith() takes the string and returns a boolean value by checking if the string starts with the searchValue.

let refString = "Hello World!";
let regExp = 'Hello';
let searchString = refString.startsWith(regExp);
console.log(searchString);

Output:

true

Example Codes: Use the position Parameter Value for the string.startsWith() Method

When a position is specified, string.startsWith() returns a boolean value based on the match between searchValue and the characters of the string. In the example below, we passed the searchValue with the position to check if the value starts the specified index position.

let string = "Typing the code.";
let strWord = 'code';
let searchString = string.startsWith(strWord, 11);
console.log(searchString);

Output:

true

Example Codes: Use a Punctuation in the searchValue Parameter for the string.startsWith() Method

The string.startsWith() method is case-sensitive. The startsWith() method returns true by checking the starting alphabets or punctuation marks from the searchValue.

When the characters in searchValue are not an exact match with the starting position of the given string, the string.startsWith() returns false. To check the resulting boolean value, we passed a different searchValue in the following example.

let string = "Welcome to 'coding'.";
let searchString = string.startsWith("'cod", 11);
let refString = string.startsWith("welcome", 0);
console.log(searchString);
console.log(refString);

Output:

true
false

The string.startsWith() method checks the string or substring starts with specific characters. With the method, the users determine whether or not a particular index position of a string begins with certain characters.