SOURCE

Function.prototype.bind2 = function (context){
    let self = this;
    let args = [].slice.call(arguments,1) //闭包存取参数
    return function(){
        let _args = [].slice.call(arguments)
        return self.apply(context,args.concat(_args))
    }
}

// 为上下文添加函数 字符创创建参数 eval执行函数 删除函数  call参数是多个，apply参数是数组
Function.prototype.myCall = function (context){
    var context = context || window;
    context.fn = this
    let args = []
    for(let i = 1; i < arguments.length; i++){
        args.push('arguments[' + i + ']')
    }
    eval('context.fn(' + args + ')')

    delete context.fn
    
}
Function.prototype.myApply = function (context,arr){
    var context = context || window;
    context.fn = this
    if(!arr){
        context.fn()
    }else{
        let args = []
        for(let i = 0; i < arr.length; i++){
            args.push('arr[' + i + ']')
        }
        eval('context.fn(' + args + ')')
    }
    delete context.fn
    
}

var foo = {
    value: 1
};

function bar(name, age) {
    console.log(name)
    console.log(age)
    console.log(this.value);
}

bar.myCall(foo, 'kevin',18);