在JavaScript中创建树状结构

Question

How can I have a reference to an object in javascript? I have the following code:

// define nodes
var NodeA = new Object();
var NodeB = new Object();

NodeA = {
    name: "A",
    children: [
        NodeB
    ]
}

NodeB = {
    name: "B",
    children: []
};

var test = NodeA.children[0].name;
// How can I make test = "A" ???  <----------------
alert(test);

I know that if I create NodeB before creating NodeA it will solve my problem.

Answer 1

You can use Object.assign to assign properties to NodeB instead of setting NodeB to be a reference to a entirely new object:

 var NodeB = {}; var NodeA = { name: "A", children: [ NodeB ] } Object.assign( NodeB, { name: "B", children: [] } ); var test = NodeA.children[0].name; alert(test); 

Note that for Internet Explorer of Object.assign support you would need to use the Polyfill . You could also just assign the properties to the existing object instead of using object literal notation to create a new one:

 var NodeB = {}; var NodeA = { name: "A", children: [ NodeB ] } NodeB.name = "B"; NodeB.children = []; var test = NodeA.children[0].name; alert(test); 

Answer 2

Why not use a function constructor:

 function Node(name) { this.name = name, this.children = []; } var nodeA = new Node('A'), nodeB = new Node('B'); nodeA.children.push(nodeB); document.write(nodeA.children[0].name); document.write('<pre>' + JSON.stringify(nodeA, 0, 4) + '</pre>'); 

Answer 3

When you assign a new value you are removing the reference of the object and then you cannot access to the object that inside children array

NodeB = {
    name: "B",
    children: []
};

You can use dot notation to assign a new properties:

NodeB.name = "B";
NodeB.children = [];

Example:

 var NodeA = new Object(); var NodeB = new Object(); NodeA = { name: "A", children: [ NodeB ] } NodeB.name = "B"; NodeB.children = []; var test = NodeA.children[0].name; alert(test);