Check if String is Empty in JavaScript

To check if a given string is empty in JavaScript, compare the string with an empty string using the Equal-to comparison operator.

The boolean expression that compares the string str and an empty string is:

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str == ''

Let us write an if-else statement with this condition. If the value of str is an empty string, the above expression returns true and if block executes; otherwise the condition returns false and else block executes.

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if (str == '') {
  console.log('str is empty');
} else {
  console.log('str is not empty');
}

Examples

Let us go through some examples on how to check if a string is empty or not in JavaScript. We have also include detailed explanations for each example.

Example 1: Empty String

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// Example 1: Empty String
var str = ''; // Initialize a variable with an empty string
if (str == '') { // Check if the string is empty
  console.log('str is empty'); // If true, print 'str is empty'
} else {
  console.log('str is not empty'); // Otherwise, print 'str is not empty'
}

Explanation: In this example, we define a variable str and assign it an empty string (''). Using an if statement, we check whether str equals an empty string. Since the condition evaluates to true, the program outputs str is empty.

Output: str is empty

Example 2: Non-Empty String

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// Example 2: Non-Empty String
var str = 'apple'; // Initialize a variable with a non-empty string
if (str == '') { // Check if the string is empty
  console.log('str is empty'); // If true, print 'str is empty'
} else {
  console.log('str is not empty'); // Otherwise, print 'str is not empty'
}

Explanation: In this example, we define a variable str and assign it a non-empty string ('apple'). Using an if statement, we check whether str equals an empty string. Since the condition evaluates to false, the program executes the else block and outputs str is not empty.

Output: str is not empty

Conclusion

In this JavaScript Tutorial, we learned how to check if a given string is empty or not using the Equal-to comparison operator, with detailed example programs and explanations.