d3.js nest.key()用法及代码示例

D3.js中的nest.key()函数用于注册一个新的键函数，该键函数将为输入数组中的每个元素调用。每当注册新 key 时，都会将其推入数组的末尾。

用法:

nest.keys(key)

参数：

它仅采用一个参数，即键函数。

返回：它返回一个字符串标识符。

下面给出了一些示例，可以更好地解释该函数。

范例1：

<!DOCTYPE html> 
<html lang="en"> 
<head> 
  <meta charset="UTF-8"> 
  <meta name="viewport" 
        content="width=device-width,  
                 initial-scale=1.0"> 
  <title>Document</title> 
</head> 
<style> 
  .originalColor{ 
    height:100px; 
    width:100px; 
  } 
  .darkerColor{ 
    height:100px; 
    width:100px; 
  } 
</style> 
<body> 
    
  <!-- Fetching from CDN of D3.js -->
  <script type = "text/javascript" 
          src =  
"https://d3js.org/d3.v4.min.js"></script> 
  <script> 
    let collection=[ 
      {val:"val1"}, 
      {val:"val2"}, 
      {val:"val3"}, 
      {val:"val4"} 
    ] 
    let data=d3.nest().key((d)=>{return d.val}) 
                      .entries(collection) 
    console.log(data); 
  </script> 
</body> 
</html>

输出：

范例2：

<!DOCTYPE html> 
<html lang="en"> 
<head> 
  <meta charset="UTF-8"> 
  <meta name="viewport" 
        content="width=device-width, 
                 initial-scale=1.0"> 
  <title>Document</title> 
</head> 
<style> 
  .originalColor{ 
    height:100px; 
    width:100px; 
  } 
  .darkerColor{ 
    height:100px; 
    width:100px; 
  } 
</style> 
<body> 
    
  <!--fetching from CDN of D3.js -->
  <script type = "text/javascript"
          src =  
"https://d3js.org/d3.v4.min.js"> 
   </script> 
  <script> 
    let collection=[ 
      {val:"val1", data:"data1", anotherData:"data1"}, 
      {val:"val2", data:"data2", anotherData:"data2"}, 
      {val:"val3", data:"data3", anotherData:"data3"}, 
      {val:"val4", data:"data4", anotherData:"data4"} 
    ] 
    //key is added 
    let data=d3.nest().key((d)=>{return d.val}) 
                      //another key is nested and added 
                      .key((d)=>{return d.data}) 
                      //another key is added and nested 
                      .key((d)=>{return d.anotherData}) 
                      .entries(collection) 
    console.log(data); 
  </script> 
</body> 
</html>

输出：

相关用法

注：本文由纯净天空筛选整理自tarun007大神的英文原创作品 D3.js nest.key() Function。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。