Javascript operators can be divided into: 1. Arithmetic operators, used to perform common mathematical operations; 2. Assignment operators, used to assign values to variables; 3. String operators; 4. Auto-increment , decrement operator; 5. comparison operator; 6. logical operator; 7. ternary operator; 8. bitwise operator.
The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.
Arithmetic operators
Arithmetic operators are used to perform common mathematical operations, such as addition, subtraction, multiplication, division, etc., as shown in the table below The arithmetic operators supported in JavaScript are listed in:
Operator | Description | Example |
---|---|---|
Addition operator | x y means calculating the sum of x plus y | |
- | Subtraction Operator | x - y means to calculate the difference of x minus y |
* | Multiplication operator | x * y means Calculate the product of x times y |
/ | Division operator | x / y means to calculate the quotient of x divided by y |
% | Modulo (remainder) operator | x % y means calculating the remainder of x divided by y |
The sample code is as follows:
var x = 10, y = 4; console.log("x + y =", x + y); // 输出:x + y = 14 console.log("x - y =", x - y); // 输出:x - y = 6 console.log("x * y =", x * y); // 输出:x * y = 40 console.log("x / y =", x / y); // 输出:x / y = 2.5 console.log("x % y =", x % y); // 输出:x % y = 2
In the above code, the content in double quotes is a string , so the operators will be output as they are and will not participate in the operation.
Assignment operator
The assignment operator is used to assign values to variables. The following table lists the assignment operations supported in JavaScript. Symbols:
Description | Example | |
---|---|---|
The simplest assignment operator, assigns the value on the right side of the operator to the variable on the left side of the operator | x = 10 means assigning the variable x to 10 | |
Perform the addition operation first, and then assign the result to the variable on the left side of the operator | x = y is equivalent to x = x y | |
Perform subtraction first, and then assign the result to the variable on the left side of the operator | x -= y is equivalent to x = x - y | |
Perform multiplication first, and then assign the result to the variable on the left side of the operator | x *= y is equivalent to x = x * y | |
Perform the division operation first, and then assign the result to the variable on the left side of the operator | x /= y is equivalent to x = x / y | |
First perform the modulo operation, and then assign the result to the variable on the left side of the operator | x %= y is equivalent to x = x % y |
复制纯文本复制
var x = 10; x += 20; console.log(x); // 输出:30 var x = 12, y = 7; x -= y; console.log(x); // 输出:5 x = 5; x *= 25; console.log(x); // 输出:125 x = 50; x /= 10; console.log(x); // 输出:5 x = 100; x %= 15; console.log(x); // 输出:10
String operatorsThe
and =
operators in JavaScript can perform mathematical operations in addition to , can also be used to splice strings, where:
## The
# =
The sample code is as follows: 复制纯文本复制
var x = "Hello "; var y = "World!"; var z = x + y; console.log(z); // 输出:Hello World! x += y; console.log(x); // 输出:Hello World!
The auto-increment and auto-decrement operators are used to perform auto-increment (1) and auto-decrement (-1) operations on the value of a variable. They are listed in the following table. Increment and decrement operators supported in JavaScript:
Influence | x | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Increments x by 1 and returns the value of x | x | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Returns the value of x, and then adds 1 to x | --x | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Decrease x by 1, and then return the value of x | x-- | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Return the value of x, Then reduce x by 1 |
运算符 | 名称 | 示例 |
---|---|---|
== | 等于 | x == y 表示如果 x 等于 y,则为真 |
=== | 全等 | x === y 表示如果 x 等于 y,并且 x 和 y 的类型也相同,则为真 |
!= | 不相等 | x != y 表示如果 x 不等于 y,则为真 |
!== | 不全等 | x !== y 表示如果 x 不等于 y,或者 x 和 y 的类型不同,则为真 |
< | 小于 | x < y 表示如果 x 小于 y,则为真 |
> | 大于 | x > y 表示如果 x 大于 y,则为真 |
>= | 大于或等于 | x >= y 表示如果 x 大于或等于 y,则为真 |
<= | 小于或等于 | x <= y 表示如果 x 小于或等于 y,则为真 |
示例代码如下:
var x = 25; var y = 35; var z = "25"; console.log(x == z); // 输出: true console.log(x === z); // 输出: false console.log(x != y); // 输出: true console.log(x !== z); // 输出: true console.log(x < y); // 输出: true console.log(x > y); // 输出: false console.log(x <= y); // 输出: true console.log(x >= y); // 输出: false
逻辑运算符
逻辑运算符通常用来组合多个表达式,逻辑运算符的运算结果是一个布尔值,只能有两种结果,不是 true 就是 false。下表中列举了 JavaScript 中支持的逻辑运算符:
运算符 | 名称 | 示例 |
---|---|---|
&& | 逻辑与 | x && y 表示如果 x 和 y 都为真,则为真 |
|| | 逻辑或 | x || y 表示如果 x 或 y 有一个为真,则为真 |
! | 逻辑非 | !x 表示如果 x 不为真,则为真 |
示例代码如下:
var year = 2021; // 闰年可以被 400 整除,也可以被 4 整除,但不能被 100 整除 if((year % 400 == 0) || ((year % 100 != 0) && (year % 4 == 0))){ console.log(year + " 年是闰年。"); } else{ console.log(year + " 年是平年。"); }
三元运算符
三元运算符(也被称为条件运算符),由一个问号和一个冒号组成,语法格式如下:
条件表达式 ? 表达式1 : 表达式2 ;
如果“条件表达式”的结果为真(true),则执行“表达式1”中的代码,否则就执行“表达式2”中的代码。
示例代码如下:
var x = 11, y = 20; x > y ? console.log("x 大于 y") : console.log("x 小于 y"); // 输出:x 小于 y
位运算符
位运算符用来对二进制位进行操作,JavaScript 中支持的位运算符如下表所示:
运算符 | 描述 | 示例 |
---|---|---|
& | 按位与:如果对应的二进制位都为 1,则该二进制位为 1 | 5 & 1 等同于 0101 & 0001 结果为 0001,十进制结果为 1 |
| | 按位或:如果对应的二进制位有一个为 1,则该二进制位为 1 | 5 | 1 等同于 0101 | 0001 结果为 0101,十进制结果为 5 |
^ | 按位异或:如果对应的二进制位只有一个为 1,则该二进制位为 1 | 5 ^ 1 等同于 0101 ^ 0001 结果为 0100,十进制结果为 4 |
~ | 按位非:反转所有二进制位,即 1 转换为 0,0 转换为 1 | ~5 等同于 ~0101 结果为 1010,十进制结果为 -6 |
<< | 按位左移:将所有二进制位统一向左移动指定的位数,并在最右侧补 0 | 5 << 1 等同于 0101 << 1 结果为 1010,十进制结果为 10 |
>> | 按位右移(有符号右移):将所有二进制位统一向右移动指定的位数,并拷贝最左侧的位来填充左侧 | 5 >> 1 等同于 0101 >> 1 结果为 0010,十进制结果为 2 |
>>> | 按位右移零(无符号右移):将所有二进制位统一向右移动指定的位数,并在最左侧补 0 | 5 >>> 1 等同于 0101 >>> 1 结果为 0010,十进制结果为 2 |
示例代码如下:
var a = 5 & 1, b = 5 | 1, c = 5 ^ 1, d = ~ 5, e = 5 << 1, f = 5 >> 1, g = 5 >>> 1; console.log(a); // 输出:1 console.log(b); // 输出:5 console.log(c); // 输出:4 console.log(d); // 输出:-6 console.log(e); // 输出:10 console.log(f); // 输出:2 console.log(g); // 输出:2
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