Summary of 6 operators in JavaScript

This article mainly introduces the summary of 6 operators in JavaScript. This article summarizes arithmetic operators, assignment operators, comparison operators, ternary operators, logical operators, string concatenation operators, etc., which are required Friends can refer to

JavaScript operators mainly include:

1. ##arithmetic operators

2. Assignment operator

3. Comparison operator

4. Ternary operator

5. Logical operator

6. String concatenation operator

Arithmetic operator

OperatorExplanationExampleOperation result##+-*/% Both operands are required to be integers++ Will have no effect on Boolean values ​​and NULL ++y (prefix)-- Will have no effect on Boolean values ​​and NULL --y (front minus)For pre-addition and post-addition, the result after execution is the variable plus 1. The difference The return results are different during execution. Please refer to the following two examples:

Add	y = 2+1	#y = 3
minus	y = 2-1	y = 1
times	y = 2*3	#y = 6
Division, the return result is a floating point type	y = 6/3	y = 2
Find the remainder, and the returned result is a floating point type	y = 6%4	y = 2
increment , divided into pre-adding and post-adding	y = 2	y++ (post-addition) y = 3
Decreasing, divided into front decrease and back decrease	y = 2	y--(post-subtraction) y = 1

The code is as follows:

var x = 2;
alert(++x); //输出：3
alert(x); //输出：3
var y = 2;
alert(y++); //输出：2
alert(y); //输出：3

The same goes for decrement.

Assignment operator

Assignment operator = is used for assignment operation. The assignment operator is used to assign the value on the right to the variable on the left. Set y = 6, see the table below:

Operator=# #+=y += 1y = y+1y = 7-=y -= 1y = y-1y = 5*=y *= 2y = y*2y = 12y /= 2y %= 4Assignment operators can be nested using Assignment operators can be nested:

Example	is equivalent to the	operation Result
y = 6	�	y = 6
			##/=
y = y/2	y = 3		%=
y = y%4	y = 2

Code As follows:

y = (x = 2) + 5;    //结果： x=2，y=7

Comparison operator

OperatorExplanation is equal toEqual (values ​​and types must be compared) 2 === "2"TRUE is not equal, and can also be written as 2 == 3TRUE> is greater than 2 > 3FALSELess than2 TRUE2 >= 32 Comparison operators can also be used for string comparisons. Ternary operator

Example	Operation result		==
2 == 3	FALSE		===
2 === 2		FALSE	##!=
	##>=	Greater than or equal to
FALSE			Less than or equal to
TRUE

Ternary can be regarded as a special comparison operator:

The code is as follows:

(expr1) ? (expr2) : (expr3)

Syntax explanation: When expr1 evaluates to TRUE, the value of the entire expression is expr2, otherwise it is expr3.

Example:

The code is as follows:

x = 2;
y = (x == 2) ? x : 1;
alert(y); //输出：2

This example determines whether the value of x is equal to 2. If x is equal to 2, then the value of y is equal to x (that is, equal to 2), otherwise y is equal to 1.

Tip

To avoid errors, it is a good idea to enclose each expression of the ternary operator in parentheses.

Logical Operator

Operator

ExplanationExamplex = 2; y = 6;x = 2; y = 6;x = 2; y = 6;

Operation result		&&	Logical AND (and)
x && y > 5	FALSE	||	Logical OR
x && y > 5	TRUE	!	Logical negation, take the opposite side of logic
!(x > y)	TRUE	字符串连接运算符 连接运算符 + 主要用于连接两个字符串或字符串变量。因此，在对字符串或字符串变量使用该运算符时，并不是对它们做加法计算。 例子： 代码如下: x = "beijing"; y = x + "你好！"; //结果：y = "beijing你好！" // 要想在两个字符串之间增加空格，需要把空格插入一个字符串之中： y = x + " 你好！"; //结果：y = "beijing 你好！" 当对字符串和数字做连接（加法）运算时，会将数字先转换成字符串再连接（相加）：  代码如下: x = 25; y = "我今年" + x + "岁"; //结果：y = "我今年25岁"

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