Bound mixin

bound.js

function Bind(){
    var i,fn;

    /**
     * holds the generated bound function collection
     * @property bound
     * @protected
     * @type object
     */
    this.bound = function(name){
        if (!this.bound[name]){
            try {
                this.bound[name] = this[name].bind(this);
            } catch (e) {
                console.warn("Trying to bind undefined method " + name);
                return;
            } 
        }

        return this.bound[name];
    };

    if (!this.bind) return;
};

//usage

class a{
  constructor(){
    Bind.call(this);
    
    document.addEventListener('click', this.bound('onClick'));
  }
  
  onClick(){
    console.log('click!');
  }
}