Question

所以我还在学习数组和对象，而且我有点卡住了。我举了一个对象数组的例子：

var something = {candy:[{name:"snickers", price:2},
                    {name:"bounty", price:3},
                    {name:"mars", price:4}]};

Object.keys(something.candy).filter(function(obj){
return console.log(something.candy[obj].name);
})

1。问题 - 为什么写作时不起作用：

var candy1 = Object.keys(something.candy);
candy1.filter(function(obj){
return console.log(obj.name);
});

这几乎与上面的代码含义相同吗？

2.Question切片是如何工作的，拼接不是???

Object.keys(something.candy).filter(function(obj){
return console.log(something.candy[obj].name.slice(0,3));
})

Object.keys(something.candy).filter(function(obj){
return a(something.candy[obj].name.splice(1,3));
})

Answer 1

在学习这些内容时，将每个部分拆开并查看是有帮助的。例如，您有一个对象：

＆＃13;

var something = {candy:[{name:"snickers", price:2},
                {name:"bounty", price:3},
                {name:"mars", price:4}]};

// what is something.candy:

console.log("candy:", something.candy)

// an array -- so what do you get with Object.keys?

var candy1 = Object.keys(something.candy)
console.log("keys:", candy1)

// just the indexes!

// So when you try to filter
candy1.filter(function(obj){
    // there is no obj.name becuase each object is just a number
    return console.log(obj);
});

＆＃13;

我想你想这样做：

＆＃13;

var something = {candy:[{name:"snickers", price:2},
                    {name:"bounty", price:3},
                    {name:"mars", price:4}]};

var select = something.candy.filter(obj => {
  console.log(obj.name) // look at them all
  return obj.name === "mars" // just pick this one
})

console.log("filtered: ", select)

＆＃13;

Object.keys，切片和拼接

1 个答案: