How to check if a string is empty in JavaScript

You can use the length property to check if a string is empty in JavaScript. If the string's length is equal to 0, then it is empty. Otherwise, the string is not empty.

const str = ''

if (str.length === 0) {
  console.log(`String is empty ✅`)
} else {
  console.log(`String is not empty ❌`)
}

// String is empty ✅

If the string contains leading or trailing whitespace, you should use the trim() method to remove whitespace before checking if it is empty:

const str = '   '

if (str.trim().length === 0) {
  console.log(`String is empty ✅`)
} else {
  console.log(`String is not empty ❌`)
}

// String is empty ✅

The trim() method removes the leading and trailing spaces from a string. It returns an empty string if the string only contains spaces.

Alternatively, you could also use the strict equality operator (===) to check whether a string is empty or not:

const str = ''

console.log(str === '')             // true
console.log(0 === '')               // false
console.log(false === '')           // false
console.log([] === '')              // false
console.log(null === '')            // false
console.log(undefined === '')       // false

As you can see above, the strict equality operator returns false for null, undefined, and false values in the comparison because these are special values.

To check if a string is truthy and contains one or more characters, use the following code:

const str = 'js'

if (str) {
  // `str` variable is NOT false, undefined,
  // null, empty string, NaN
  console.log(`String is truthy 💯`)
}

// String is truthy 💯

A variable is truthy if it is not an empty string, 0, null, undefined, false, or NaN.

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