D3.js ordinal.copy()函数

ordinal.copy()函数用于创建和返回序数比例的精确副本。原始比例的任何更改都不会影响复制比例，反之亦然。

句法：

ordinal.copy();

参数：此方法不带任何参数。

返回值：此方法返回原始比例的副本。

示例 1：

HTML

  

    
    
  
    
    

  

    
  
        // Creating the Ordinal scale.
        var ordinal = d3.scaleThreshold()
  
            // Setting domain for the scale
            .domain([1, 2, 3, 4])
            .range([10, 20, 30, 40]);
  
        // Making copy of the scale.
        var ordinalCopy = ordinal.copy();
        console.log("The value of ordinalCopy(1) is: ",
                ordinalCopy(1));
        console.log("The value of ordinalCopy(2) is: ",
                ordinalCopy(2));
        console.log("The value of ordinal(1) is: ",
                ordinal(1));
        console.log("The value of ordinal(2) is: ",
                ordinal(2));
    

  

输出：

示例 2：

HTML

  

    
    
  
    
    

  

    
  
        // Creating the Ordinal scale.
        var ordinal = d3.scaleThreshold()
          
            // Setting domain for the scale
            .domain([1, 2, 3, 4])
            .range([10, 20, 30, 40, 50]);
          
        console.log("The value of ordinal(3) is: ",
                ordinal(3));
        console.log("The value of ordinal(4) is: ",
                ordinal(4));
  
        // Making copy of the scale.
        var ordinalCopy = ordinal.copy();
  
        // making change in the original scale.
        ordinal.range(["The range of the "
                + "original scale is change"]);
        console.log("The value of ordinalCopy(3) is: ",
                ordinalCopy(3));
        console.log("The value of ordinalCopy(4) is: ",
                ordinalCopy(4));
        console.log("The value of ordinal(3) is: ",
                ordinal(3));
        console.log("The value of ordinal(4) is: ",
                ordinal(4));
    

  

输出：