camel-to-kebab/dist/camel-to-kebab.js

Convert camelCase inputs to kebab-case outputs.

// github.com/pineapplemachine/camel-to-kebab-js
// zlib/libpng license https://opensource.org/licenses/zlib-license.php
// Copyright (c) 2018 Sophie Kirschner (sophiek@pineapplemachine.com)

// Converts a camelCase input string to kebab-case output.
// If the input is not a string, it will be coerced to one.
function camelToKebabCase(text){
    // When the input was null or undefined, return that same value
    if(text === null || text === undefined){
        return text;
    }
    // The output string, to be built in the loop
    var result = "";
    // Counts consecutive upper-case characters
    var upper = 0;
    // True when the last character was a number and false when the last
    // character was something other than a number
    var numeric = undefined;
    // Enumerate characters in the input string
    var string = String(text);
    for(var i = 0; i < string.length; i++){
        var ch = string[i];
        var chLower = ch.toLowerCase();
        // If it's an upper-case letter (not preceded by ascii whitespace):
        if(ch !== chLower){
            var prev = result[result.length - 1];
            // Handle cases like "innerHTML" => "inner-html",
            // NOT "inner-h-t-m-l"
            if(upper > 1 && result.length > 1){
                result = result.slice(0, result.length - 2) + prev;
            }
            // Add a hyphen (but not at the beginning of the output, and not
            // two in a row, and not after whitespace)
            if(result.length && prev !== "-" &&
                prev !== " " && prev !== "\t" && prev !== "\r" && prev !== "\n"
            ){
                result += "-";
            }
            // Append the lower-case character
            result += chLower;
            // Update upper-case and numeric state
            upper++;
            numeric = false;
        // If it's a number:
        }else if(
            ch === "0" || ch === "1" || ch === "2" || ch === "3" ||
            ch === "4" || ch === "5" || ch === "6" || ch === "7" ||
            ch === "8" || ch === "9"
        ){
            // Add a hyphen if the last character wasn't a number (but not
            // two hyphens in a row)
            if(numeric === false && result[result.length - 1] !== "-"){
                result += "-";
            }
            // Append the numeric character
            result += ch;
            // Update upper-case and numeric state
            upper = 0;
            numeric = true;
        // If it's not upper case or a number, but the last character was numeric:
        }else if(numeric && result[result.length - 1] !== "-"){
            // Append a hyphen and then the character
            result += "-" + ch;
            // Update upper-case and numeric state
            upper = 0;
            numeric = false;
        // If it's not upper case or numeric, and not following a number:
        }else{
            // Append the character
            result += ch;
            // Update upper-case and numeric state
            upper = 0;
            numeric = false;
        }
    }
    // Handle cases like "innerHTML" => "inner-html", NOT "inner-htm-l"
    if(upper > 1 && result.length > 1){
        result = result.slice(0, result.length - 2) + result[result.length - 1];
    }
    // All done!
    return result;
}

// Export it
if(typeof(module) !== "undefined"){
    module.exports = camelToKebabCase;
    module.exports.default = camelToKebabCase;
}
if(typeof(window) !== "undefined"){
    window.camelToKebabCase = camelToKebabCase;
}