jsの関数を再ロードします.

    function overLoading () {
        switch(arguments.length) {
            case 0:
                //        
            break;
            case 1:
                //        
            break;
            case 2:
                // ...
        }

    }
    

    // people        find  ，
    //           ，   people.values       ，
    //           ，  firstName         value 
    //           ，  firstName  lastName     value 

    var people = {
        values: ["Dean Edwards", "Alex Russell", "Dean Tom"]
    }
    addMethod(people, 'find', function () {})
    addMethod(people, 'find', function(a) {})
    addMethod(people, 'find', function(a, b) {})

    function addMethod (object, name, fn) {
        let old = object[name]
        object[name] = function () {
            if(arguments.length === fn.length) {
                return fn.apply(this, arguments)
            } else if(typeof old === 'function') {
                return old.apply(this, arguments)
            }
        }
    }

    //       addMethod     people.find    
    addMethod(people, 'find', function(){
        return this.values
    })
    addMethod(people, 'find', function(firstName) {
        let ret = [] 
        for(var i =0 ;i < this.values.length; i++) {
            if(this.values[i].indexOf(firstName) === 0) {
                ret.push(this.values[i])
            }
        }
        return ret;
    })
    addMethod(people, 'find', function(firstName, lastName) {
        let ret = []
        for(var i =0 ;i < this.values.length; i++) {
            if(this.values[i] === firstName + ' ' + lastName) {
                ret.push(this.values[i])
            }
        }
        return ret
    })

    console.log(people.find())   //["Dean Edwards", "Alex Russell", "Dean Tom"]
    console.log(people.find('Dean'))  // ["Dean Edwards", "Dean Tom"]
    console.log(people.find('Dean', 'Edwards')) //["Dean Edwards"]