Changing the case of a string using JavaScript

We are required to write a JavaScript function that takes in a string and converts it to snake case.

Snake case is basically a style of writing strings by replacing the spaces with '_' and converting the first letter of each word to lowercase.

Example

The code for this will be ?

const str = 'This is a simple sentence';
const toSnakeCase = (str = '') => {
    const strArr = str.split(' ');
    const snakeArr = strArr.reduce((acc, val) => {
        return acc.concat(val.toLowerCase());
    }, []);
    return snakeArr.join('_');
};
console.log(toSnakeCase(str));

Output

The output in the console will be ?

this_is_a_simple_sentence

Alternative Approach Using map()

We can also use the map() method for a more concise solution:

const str = 'Hello World JavaScript';
const toSnakeCase = (str = '') => {
    return str.split(' ')
             .map(word => word.toLowerCase())
             .join('_');
};
console.log(toSnakeCase(str));

hello_world_javascript

Handling Special Characters

For more robust snake case conversion that handles special characters:

const str = 'This-is a Complex_String!';
const toSnakeCase = (str = '') => {
    return str.replace(/[^a-zA-Z0-9]/g, ' ')  // Replace non-alphanumeric with space
             .split(' ')
             .filter(word => word.length > 0)   // Remove empty strings
             .map(word => word.toLowerCase())
             .join('_');
};
console.log(toSnakeCase(str));

this_is_a_complex_string

Conclusion

Snake case conversion can be achieved using split(), toLowerCase(), and join() methods. The map() approach provides cleaner code, while regex handling ensures robust conversion of complex strings.