How to convert a string to snake case using JavaScript ?

In this article, we are given a string in and the task is to write a JavaScript code to convert the given string into a snake case and print the modified string. 

Examples:

Input: GeeksForGeeks
Output: geeks_for_geeks
Input: CamelCaseToSnakeCase
Output: camel_case_to_snake_case

Approach: We use the match(), map(), join(), and toLowerCase() methods to convert a given string into a snake case string. The match() method is used to match the given string with the pattern and then use map() and toLowerCase() methods to convert the given string into lower case and then use join() method to join the string using underscore (_). 

Example: This example shows the use of the above-explained approach.

Javascript

<script>
    function snake_case_string(str) {
        return str && str.match(
    /[A-Z]{2,}(?=[A-Z][a-z]+[0-9]*|\b)|[A-Z]?[a-z]+[0-9]*|[A-Z]|[0-9]+/g)
            .map(s => s.toLowerCase())
            .join('_');
    }

    console.log(snake_case_string('GeeksForGeeks'));
    console.log(snake_case_string('Welcome to GeeksForGeeks'));
    console.log(snake_case_string('Welcome-to-GeeksForGeeks'));
    console.log(snake_case_string('Welcome_to_GeeksForGeeks'));
</script>

Output:

geeks_for_geeks
welcome_to_geeks_for_geeks
welcome_to_geeks_for_geeks
welcome_to_geeks_for_geeks

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