小编MFr*_*ier的帖子

当我向beats数组添加项目然后console.log用户时,我在数组中获得了正确数量的项目.但是当我检查.length时,我总是得到1.尝试调用索引总是会给我'未定义',就像这样: Tom.beats[1] 我想我错过了一些明显的东西,但这是打败了我.我怀疑我滥用这种.push方法,但我不确定.任何帮助是极大的赞赏!(使用Chrome开发工具)

//The USER

function User(name, role){
    this.beats = [ ]; 

    this.name = name;
    this.role = role;

    // add beats to beats array

    this.addBeats = function(beats){ 
        return this.beats.push(beats);
   };

}

// Three New Instances. Three New Users.

var Mal = new User("Mal", "Rapper");
Mal.addBeats(["love", "cash"]);

var Dan = new User("Dan", "Producer");
Dan.addBeats(["cake", "dirt", "sally-mae"]);

var Tom = new User("Tom", "Producer");
Tom.addBeats(["Fun", "Little", "Samsung", "Turtle", "PC"]);

// Check for position in beats array

console.log(Tom.beats); 
console.log(Mal.beats); 
console.log(Dan.beats); 

console.log(Mal.beats[1]);
console.log(Dan.beats[1]); …