Question

JSON：

{
 "comments":[
    {"id":1,"author_name":null,"comment_text":null,"url":"http://localhost:3000/comments/1.json"},
    {"id":2,"author_name":null,"comment_text":null,"url":"http://localhost:3000/comments/2.json"},{"id":3,"author_name":"Yerassyl","comment_text":"Hello world!","url":"http://localhost:3000/comments/3.json"},
    {"id":4,"author_name":"Yerassyl","comment_text":"hi there","url":"http://localhost:3000/comments/4.json"}
 ]
}

如何在评论中迭代每条评论。我想要这样的东西：

//pseudocode
comments.each(key,value){
// do something
}

我试过了地图，但地图是用于数组的。

编辑：如果我删除根节点'comments'我可以使用.map：

var commentNodes = this.props.comments.map(function(comment,index){
      });

忽略this.props，它实际上是React.js console.log（this.props.comments）返回带有根节点'comments'的json对象

Answer 1

假设你有

var obj = {
 "comments":[
    {"id":1,"author_name":null,"comment_text":null,"url":"http://localhost:3000/comments/1.json"},
    {"id":2,"author_name":null,"comment_text":null,"url":"http://localhost:3000/comments/2.json"},{"id":3,"author_name":"Yerassyl","comment_text":"Hello world!","url":"http://localhost:3000/comments/3.json"},
    {"id":4,"author_name":"Yerassyl","comment_text":"hi there","url":"http://localhost:3000/comments/4.json"}
 ]
};

你可以这样做，例如，

obj.comments.map(function (comment) {
    console.log(comment);
});

Answer 2

假设您已经class Test: def __init__(self, val): self.a = val T = Test (10) T1 = Test(20) print str(T.a) + '__' + str(T1.a)了字符串，可以使用forEach进行迭代。 Map仅用于从现有值返回新数组。

JSON.parse

编辑：听起来像this.props.comments.comments.forEach(function(value, index) { console.log(value, index); });是根对象。因此上面的访问者

Answer 3

首先，您必须解析您的JSON数据：

var json = '{
 "comments":[
    {"id":1,"author_name":null,"comment_text":null,"url":"http://localhost:3000/comments/1.json"},
{"id":2,"author_name":null,"comment_text":null,"url":"http://localhost:3000/comments/2.json"},{"id":3,"author_name":"Yerassyl","comment_text":"Hello world!","url":"http://localhost:3000/comments/3.json"},
{"id":4,"author_name":"Yerassyl","comment_text":"hi there","url":"http://localhost:3000/comments/4.json"}
 ]
}';
var data = JSON.parse(json);

然后你可以继续循环并完成这样的评论：

data.comments.forEach(function(comment, index) {
    console.log("Comments["+index+"]: "+comment);
});

注意：

解析完JSON后，您将获得一个包含一系列注释的对象，以便您可以轻松地使用所有 Array.prototype 方法，包括forEach和{{1 }}

在javascript中迭代json哈希

3 个答案: