Compare two strings in JavaScript

This post will discuss how to compare two strings in JavaScript.

1. Using `localeCompare()` method

The localeCompare() method compares a string to another string and returns an integer indicating whether the string comes before, after, or equivalent to the specified string. It returns a negative number if the string occurs before the compare string; positive if the string occurs after the compare string; 0 if both strings are equivalent.

let x = 'ABC';

let y = 'ABD';

let ret = x.localeCompare(y)

if (ret < 1) {

console.log(`${x} occurs before ${y}`);

}

else if (ret > 1) {

console.log(`${x} occurs after ${y}`);

}

else {

console.log(`${x} is equivalent to ${y}`);

}

Output: ABC occurs before ABD

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2. Custom comparison function

You can also write our own comparison function to compare strings. The following code example shows how to implement this:

function compare(x, y)

{

if (x < y) {

return -1;

}

if (x > y) {

return 1;

}

return 0;

}

let x = 'ABC';

let y = 'ABD';

let ret = compare(x, y);

if (ret < 1) {

console.log(`${x} occurs before ${y}`);

}

else if (ret > 1) {

console.log(`${x} occurs after ${y}`);

}

else {

console.log(`${x} is equivalent to ${y}`);

}

Output: ABC occurs before ABD

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You can shorten the above method to:

function compare(x, y) {

return (x < y ? -1 : (x > y ? 1 : 0));

}

3. Using Underscore/Lodash Library

If you’re using the Underscore or Lodash library, consider using the _.isEqual method. It performs a deep comparison between two values to determine whether they are equivalent.

var _ = require('underscore');

let x = 'ABC';

let y = 'ABC';

console.log(_.isEqual(x, y));

Output: true

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That’s all about comparing two strings in JavaScript.

Compare two strings in JavaScript

1. Using localeCompare() method

2. Custom comparison function

3. Using Underscore/Lodash Library

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1. Using `localeCompare()` method