Check if String starts with a space in JavaScript

In this post, we will see how to check whether the first character in a string is a space or not using Javascript.

To check if a string starts with a space or not we can use:

RegExp test method,
String match method with regExp, or
String startsWith method

Let’s see the above-mentioned methods with examples.

Using RegExp.test() method

We can call the regex test method on the following expression ^s*$ and pass on the string to detect if the string starts with a white space or not in JavaScript.

Example

function startsWithSpace(str){
  return /^s/.test(str);
}

console.log(startsWithSpace(' hello')) // true
console.log(startsWithSpace(' hello ')) // true
console.log(startsWithSpace('hello')) //false

Here, we have called the test() method on the regular expression /^s/ to match the pattern against the given string.

The / / (forward slash) indicates the start and the end of the expression.

The ^ indicate the start of a string or line.

The s matches any whitespace characters in the string, like tab, space, newline, line feed, form feed, etc.

Using match() method on string with regex

The match() is used to match a string against a regular expression. If a match is found it returns the array with the matched result. And it returns null if no match is found.

Example:

function startsWithSpace(str){
  return str.match(new RegExp( /^s/)) !== null; 
}

console.log(startsWithSpace(' hello')) //true
console.log(startsWithSpace('hello')) //false

Here, we have used the match() method on a string and passed the regex as an argument to match against the given string.

/ and / indicate the start and end of the regular expression.

^ specifies the start of the string or a line

s tells to check for white spaces in the string.

Using startsWith() method

The startsWith() method checks whether a string starts with a specific character in a given string. If the searched character is found it returns true else it returns false.

function startsWithSpace(str){
  return str.startsWith(" ");
}

console.log(startsWithSpace(' hello')) //true
console.log(startsWithSpace(' hello ')) //true
console.log(startsWithSpace('hello'))// false
console.log(startsWithSpace('hello '))// false

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