D3.js band.copy()函数

band.copy()函数用于构造并返回具有相同域和范围的当前刻度的副本。对任何比例所做的任何更改都是相互独立的，即原始比例的更改不会影响复制比例，反之亦然。

句法：

band.copy();

参数：此函数不接受任何参数。

返回值：此函数返回当前比例的副本。返回类型是一个函数。

下面给出了上面给出的函数的几个例子。

示例 1：

 
 
 
     
     
    
    
      
 
 
     
    // Creating the band scale 
    //with specified domain and range.
        var band = d3.scaleBand()
                    .domain([10, 20, 30, 40, 50])
                    .range([10, 100]);
    // Discrete values are automatically created 
    // By the band function
    // Band of the range is [10, 100]
        console.log("band(10): ", band(10));
        console.log("band(50): ", band(50));
  
        var bandCopy = band.copy();
        console.log("bandCopy(10): ", bandCopy(10));
        console.log("bandCopy(50): ", bandCopy(50));
     
 

输出：

示例 2：

 
 
 
     
     
    GeekforGeeks 
    
    
      
 
 
     
    // Creating the band scale
  // with specified domain and range.
        var band = d3.scaleBand()
                .domain([10, 20, 30, 40, 50])
                .range([1, 10]);
// Discrete values are automatically created 
    // By the band function
    // Band of the range is [1, 10]
        console.log(
"Before any type of change in original scale:");
        console.log("band(10): ", band(10));
        console.log("band(50): ", band(50));
        // Making copy of the original scale
        var bandCopy = band.copy();
        console.log(
"When the range of the original "+
"scale is changed to rangeRound:");
        // Making changes to the original scale
        band.rangeRound([1, 10]);
        console.log("band(10): ", band(10));
        console.log("band(50): ", band(50));
        console.log("Output of the copy scale:");
        console.log("bandCopy(10): ", bandCopy(10));
        console.log("bandCopy(50): ", bandCopy(50));
     
 

输出：