Once function

once.js

/**
 * Once script to make sure a function is only run once!
 */
(function(global){
 
    function once(func) {
        var ran = false, memo;
        return function() {
            if (ran) return memo;
            ran = true;
            memo = func.apply(this, arguments);
            return memo;
        };
    }
 
    if (typeof exports !== 'undefined') {
        module.exports = once;
    } else if (global.define && global.define.amd) {
        define(function(){ return once; });
    } else {
        global.once = once;
    }
 
}(this));