lineColor ={ red：'blue'，blue：'red‘}[ var ]；

Question

 $('#toggle-linecolor').click(function () {
        chart.yAxis[0].update({
            lineColor: lineColor
        });
        lineColor = { red: 'blue', blue: 'red' }[lineColor];
    });

Answer 1

它在'red'和'blue'之间切换。

假设你是这样开始的：

var lineColor = 'red';

执行此操作会将lineColor更改为“blue”

lineColor = { red: 'blue', blue: 'red' }[lineColor];
// The property [red] of that object has a value of 'blue'

lineColor // <--- 'blue'

再次执行它，它会将值切换为“red”

lineColor = { red: 'blue', blue: 'red' }[lineColor];
// The property [blue] of that object has a value of 'red'

lineColor // <---- 'red'

Answer 2

它交换/切换颜色。红色-->蓝色，蓝色-->红色

lineColor = 'blue';
lineColor = { red: 'red', blue: 'blue' }[lineColor]; // 'red'

等同于

lineColor = { red: 'red', blue: 'blue' }.blue; // 'red'

Answer 3

这是一种聪明的方法，可以将toggle实现为one liner。你可以像这样解压它：

var lineColor = 'red';
function toggleColor(){
    chart.yAxis[0].update({
        lineColor: lineColor
    });
    var opposites = { red : 'blue', blue : 'red' };
    if( lineColor == 'red' ){
        lineColor = opposites.red; // assigns 'blue' to lineColor
    }
    else if( lineColor == 'blue' ){
        lineColor = opposites.blue; // assigns 'red' to lineColor
    }

    // but you can shorten the above if/else statement to:
    lineColor = opposites[ lineColor ];

    // which can be shortened to this if you don't want to 
    // assign the opposites object to a variable:
    lineColor = { red: 'blue', blue: 'red' }[lineColor];
}

注释后编辑:可以使用两种以上的颜色创建循环序列：

opposites = { red : 'green', green : 'yellow', yellow : 'blue', blue : 'red' };

因此，如果当前颜色是红色，则更改为绿色，如果是绿色，则更改为黄色，如果是黄色，则更改为蓝色，如果是蓝色，则更改为红色：http://jsfiddle.net/p3bw04vw/