.. _wxs-operator:

:wxfrwk:`运算符 <view/wxs/04operator>`
=============================================

基本运算符
-------------------

示例代码：

.. code:: js

   var a = 10, b = 20;

   // 加法运算
   console.log(30 === a + b);
   // 减法运算
   console.log(-10 === a - b);
   // 乘法运算
   console.log(200 === a * b);
   // 除法运算
   console.log(0.5 === a / b);
   // 取余运算
   console.log(10 === a % b);
   // 加法运算（+）也可以用作字符串的拼接。
   var a = '.w' , b = 'xs';

   // 字符串拼接
   console.log('.wxs' === a + b);

一元运算符
-------------------

示例代码：

.. code:: js

  var a = 10, b = 20;

  // 自增运算
  console.log(10 === a++);
  console.log(12 === ++a);
  // 自减运算
  console.log(12 === a--);
  console.log(10 === --a);
  // 正值运算
  console.log(10 === +a);
  // 负值运算
  console.log(0-10 === -a);
  // 否运算
  console.log(-11 === ~a);
  // 取反运算
  console.log(false === !a);
  // delete 运算
  console.log(true === delete a.fake);
  // void 运算
  console.log(undefined === void a);
  // typeof 运算
  console.log("number" === typeof a);

位运算符
-------------------

示例代码：

.. code:: js

  var a = 10, b = 20;

  // 左移运算
  console.log(80 === (a << 3));
  // 无符号右移运算
  console.log(2 === (a >> 2));
  // 带符号右移运算
  console.log(2 === (a >>> 2));
  // 与运算
  console.log(2 === (a & 3));
  // 异或运算
  console.log(9 === (a ^ 3));
  // 或运算
  console.log(11 === (a | 3));

比较运算符
-------------------

示例代码：

.. code:: js

  var a = 10, b = 20;

  // 小于
  console.log(true === (a < b));
  // 大于
  console.log(false === (a > b));
  // 小于等于
  console.log(true === (a <= b));
  // 大于等于
  console.log(false === (a >= b));

等值运算符
-------------------

示例代码：

.. code:: js

  var a = 10, b = 20;

  // 等号
  console.log(false === (a == b));
  // 非等号
  console.log(true === (a != b));
  // 全等号
  console.log(false === (a === b));
  // 非全等号
  console.log(true === (a !== b));

赋值运算符
-------------------

示例代码：

.. code:: js

   var a = 10;

   a = 10;
   a *= 10;
   console.log(100 === a);

   a = 10;
   a /= 5;
   console.log(2 === a);

   a = 10;
   a %= 7;
   console.log(3 === a);

   a = 10;
   a += 5;
   console.log(15 === a);

   a = 10;
   a -= 11;
   console.log(-1 === a);

   a = 10;
   a <<= 10;
   console.log(10240 === a);

   a = 10;
   a >>= 2;
   console.log(2 === a);

   a = 10;
   a >>>= 2;
   console.log(2 === a);

   a = 10;
   a &= 3;
   console.log(2 === a);

   a = 10;
   a ^= 3;
   console.log(9 === a);

   a = 10;
   a |= 3;
   console.log(11 === a);

二元逻辑运算符
-------------------

示例代码：

.. code:: js

  var a = 10, b = 20;

  // 逻辑与
  console.log(20 === (a && b));
  // 逻辑或
  console.log(10 === (a || b));

其他运算符
-------------------

示例代码：

.. code:: js

  var a = 10, b = 20;

  //条件运算符
  console.log(20 === (a >= 10 ? a + 10 : b + 10));
  //逗号运算符
  console.log(20 === (a, b));

运算符优先级
----------------------------

+--------+---------------------------+------------+----------+
| 优先级 |          运算符           |    说明    |  结合性  |
+========+===========================+============+==========+
| 20     | ( ... )                   | 括号       | N / A    |
+--------+---------------------------+------------+----------+
| 19     | ... ....                  | 成员访问   | 从左到右 |
+--------+---------------------------+------------+----------+
|        | ... [...]                 | 成员访问   | 从左到右 |
+--------+---------------------------+------------+----------+
|        | ... (...)                 | 函数调用   | 从左到右 |
+--------+---------------------------+------------+----------+
| 17     | ... ++                    | 后置递增   | N / A    |
+--------+---------------------------+------------+----------+
|        | ... --                    | 后置递减   | N / A    |
+--------+---------------------------+------------+----------+
| 16     | ! ...                     | 逻辑非     | 从右到左 |
+--------+---------------------------+------------+----------+
|        | ~ ...                     | 按位非     | 从右到左 |
+--------+---------------------------+------------+----------+
|        | + ...                     | 一元加法   | 从右到左 |
+--------+---------------------------+------------+----------+
|        | - ...                     | 一元减法   | 从右到左 |
+--------+---------------------------+------------+----------+
|        | ++ ...                    | 前置递增   | 从右到左 |
+--------+---------------------------+------------+----------+
|        | -- ...                    | 前置递减   | 从右到左 |
+--------+---------------------------+------------+----------+
|        | typeof ...                | 类型       | 从右到左 |
+--------+---------------------------+------------+----------+
|        | void ...                  | 空虚       | 从右到左 |
+--------+---------------------------+------------+----------+
|        | delete ...                | 删除       | 从右到左 |
+--------+---------------------------+------------+----------+
| 14     | ... *...                  | 乘法       | 从左到右 |
+--------+---------------------------+------------+----------+
|        | ... /...                  | 除法       | 从左到右 |
+--------+---------------------------+------------+----------+
|        | ... %...                  | 取模       | 从左到右 |
+--------+---------------------------+------------+----------+
| 13     | ... +...                  | 加法       | 从左到右 |
+--------+---------------------------+------------+----------+
|        | ... -...                  | 减法       | 从左到右 |
+--------+---------------------------+------------+----------+
| 12     | ... <<...                 | 按位左移   | 从左到右 |
+--------+---------------------------+------------+----------+
|        | ... >>...                 | 按位右移   | 从左到右 |
+--------+---------------------------+------------+----------+
|        | ... >>>...                | 无符号右移 | 从左到右 |
+--------+---------------------------+------------+----------+
| 11     | ... <...                  | 小于       | 从左到右 |
+--------+---------------------------+------------+----------+
|        | ... <=...                 | 小于等于   | 从左到右 |
+--------+---------------------------+------------+----------+
|        | ... >...                  | 大于       | 从左到右 |
+--------+---------------------------+------------+----------+
|        | ... >=...                 | 大于等于   | 从左到右 |
+--------+---------------------------+------------+----------+
| 10     | ... ==...                 | 等号       | 从左到右 |
+--------+---------------------------+------------+----------+
|        | ... !=...                 | 非等号     | 从左到右 |
+--------+---------------------------+------------+----------+
|        | ... ===...                | 全等号     | 从左到右 |
+--------+---------------------------+------------+----------+
|        | ... !==...                | 非全等号   | 从左到右 |
+--------+---------------------------+------------+----------+
| 9      | ... &...                  | 按位与     | 从左到右 |
+--------+---------------------------+------------+----------+
| 8      | ... ^...                  | 按位异或   | 从左到右 |
+--------+---------------------------+------------+----------+
| 7      | ... ｜...                 | 按位或     | 从左到右 |
+--------+---------------------------+------------+----------+
| 6      | ... &&...                 | 逻辑与     | 从左到右 |
+--------+---------------------------+------------+----------+
| 5      | ... ｜｜...               | 逻辑或     | 从左到右 |
+--------+---------------------------+------------+----------+
| 4      | ... ... ?... ... :... ... | 条件运算符 | 从右到左 |
+--------+---------------------------+------------+----------+
| 3      | ... =...                  | 赋值       | 从右到左 |
+--------+---------------------------+------------+----------+
|        | ... +=...                 | 赋值       | 从右到左 |
+--------+---------------------------+------------+----------+
|        | ... -=...                 | 赋值       | 从右到左 |
+--------+---------------------------+------------+----------+
|        | ... *=...                 | 赋值       | 从右到左 |
+--------+---------------------------+------------+----------+
|        | ... /=...                 | 赋值       | 从右到左 |
+--------+---------------------------+------------+----------+
|        | ... %=...                 | 赋值       | 从右到左 |
+--------+---------------------------+------------+----------+
|        | ... <<=...                | 赋值       | 从右到左 |
+--------+---------------------------+------------+----------+
|        | ... >>=...                | 赋值       | 从右到左 |
+--------+---------------------------+------------+----------+
|        | ... >>>=...               | 赋值       | 从右到左 |
+--------+---------------------------+------------+----------+
|        | ... &=...                 | 赋值       | 从右到左 |
+--------+---------------------------+------------+----------+
|        | ... ^=...                 | 赋值       | 从右到左 |
+--------+---------------------------+------------+----------+
|        | ... \｜=...               | 赋值       | 从右到左 |
+--------+---------------------------+------------+----------+
| 0      | ... ,...                  | 逗号       | 从左到右 |
+--------+---------------------------+------------+----------+