JavaScript startsWith Method: Check with what character your string starts with

In this tutorial, you will learn to check if your string starts with a certain set of characters or not using the startsWith() method in JavaScipt.

JavaScipt startsWith Method

The startsWith() string method is used to determine whether a string starts with some given substring or not.

If the string starts with a specified substring then it returns true if not then return false.

The method is applied on a string and the substring is passed as the first argument to the method.

const str = "Learning to code";
console.log(str.startsWith("to")); // false
console.log(str.startsWith("Learning")); // true

Syntax of startsWith method

The syntax of startsWith() string method in javascript is:

string.startsWith(search_string [ ,position])

The method accepts 2 arguments:

1. search_string - It is the substring or a set of character to be searched at the starting of a given string.
2. position (optional) - It is an optional argument that is the position in the string from where the search for the substring is started. The default value is 0.

startsWith Method Example

# Example 1: Using startsWith method without position parameter.

const str = "To do or not to do";
console.log(str.startsWith("do")); // false
console.log(str.startsWith("To")); // true
console.log(str.startsWith("T")); // true
console.log(str.startsWith("To ")); // true

In the above example first, we check for substring 'do' which is not the starting of the calling string and return false, then we check for substring 'To' and method return true. The method also returns true for 'T' and 'To ' because the method does not count the first word but count anything that is at starting of the string.

# Example 2: Using startsWith method with position parameter.

const str = "To do or not to do";
console.log(str.startsWith("do", 3)); // true
console.log(str.startsWith("To", 0)); // true
console.log(str.startsWith("T0", 2)); // false

When using the position parameter, the starting substring is checked from a given position. So when we check to start of the string by giving position 3 it returned true.

Case-sensitivity

The startsWith() method is case sensitive, which means it treats string with the same characters but the different case as different.

Look out the following example:

const str = "Learn to code";
console.log(str.startsWith("Learn")); // true
console.log(str.startsWith("LEARN")); // false
console.log(str.startsWith("learn")); // false