freeCodeCamp/curriculum/challenges/chinese/02-javascript-algorithms-and-data-structures/basic-javascript/compound-assignment-with-augmented-subtraction.md

id, challengeType, videoUrl, forumTopicId, localeTitle

id	challengeType	videoUrl	forumTopicId	localeTitle
56533eb9ac21ba0edf2244b0	1	https://scrimba.com/c/c2Qv7AV	16660	复合赋值之 -=

Description

与+=操作符类似，-=操作符用来对一个变量进行减法赋值操作。 myVar = myVar - 5; 变量myVar等于自身减去5的值。也可以写成这种形式： myVar -= 5;

Instructions

使用-=操作符实现同样的效果。

Tests

tests:
  - text: <code>a</code>应该等于<code>5</code>。
    testString: assert(a === 5);
  - text: <code>b</code>应该等于<code>-6</code>。
    testString: assert(b === -6);
  - text: <code>c</code>应该等于<code>2</code>。
    testString: assert(c === 2);
  - text: 应该对每个变量使用<code>-=</code>操作符。
    testString: assert(code.match(/-=/g).length === 3);
  - text: 不要修改注释上面的代码。
    testString: assert(/var a = 11;/.test(code) && /var b = 9;/.test(code) && /var c = 3;/.test(code));

Challenge Seed

var a = 11;
var b = 9;
var c = 3;

// Only modify code below this line

a = a - 6;
b = b - 15;
c = c - 1;

After Test

(function(a,b,c){ return "a = " + a + ", b = " + b + ", c = " + c; })(a,b,c);

Solution

var a = 11;
var b = 9;
var c = 3;

a -= 6;
b -= 15;
c -= 1;