D3.js node.leaves()函数

d3.js 中的node.leaves()函数用于按遍历顺序返回给定分层数据的叶节点数组。

句法：

node.leaves();

参数：此函数不接受任何参数。

返回值：此函数返回一个数组。

注意：叶节点是那些没有子节点的节点。

下面给出了上面给出的函数的几个例子。

示例 1：

HTML

  

    
    
    
    

  

    
        // Constructing a tree
        var tree = {
            name: "rootNode",
            children: [
                {
                    name: "child1_leaf1"
                },
                {
                    name: "child2",
                    children: [
                        {
                            name: "grandchild1",
                            children: [
                                { name: "leaf2" }
                            ]
                        },
                    ]
                },
                {
                    name: "child3",
                    children: [
                        { name: "leaf3" },
                        { name: "leaf4" },
                    ]
                }
            ]
        };
  
        var obj = d3.hierarchy(tree);
          
        // Leaf nodes of the above given tree
        console.log("Leaf nodes are: ");
        console.log(obj.leaves());        
    

  

输出：

示例 2：以下代码演示访问叶节点的数据。

HTML

  

    
    
    
    

  

    
        // Constructing a tree
        var tree = {
            name: "rootNode",
            children: [
                {
                    name: "child1_leaf1"
                },
                {
                    name: "child2",
                    children: [
                        {
                            name: "grandchild1",
                            children: [
                                { name: "leaf2" }
                            ]
                        },
                    ]
                },
                {
                    name: "child3",
                    children: [
                        { name: "leaf3" },
                        { name: "leaf4" },
                    ]
                }
            ]
        };
  
        var obj = d3.hierarchy(tree);
          
        // Leaf nodes of the above given tree are:
        console.log(" Accessing Leaf nodes: ");
        let leafArr = obj.leaves();
        leafArr.forEach((e) => {
            console.log(e.data);
            console.log("depth: ", e.depth);
        })        
    

  

输出：