6 operators in JavaScript-Basic Knowledge-js tutorial

This article mainly introduces the summary of six operators in JavaScript. This article summarizes Arithmetic Operators, value assignment operators, comparison operators, ternary operators, logical operators, String concatenation operators, and so on, for more information, see JavaScript operators include:

1. Arithmetic Operators
2. Value assignment operator
3. Comparison Operators
4. Ternary Operators
5. Logical operators
6. String concatenation operator

Arithmetic Operators

Operator	Description	Example	Calculation Result
+	Add	Y = 2 + 1	Y = 3
-	Subtraction	Y = 2-1	Y = 1
*	Multiplication	Y = 2*3	Y = 6
/	Besides, the returned result is of the floating point type.	Y = 6/3	Y = 2
%	Return result is of the floating point type. Both operands must be integers.	Y = 6% 4	Y = 2
++	Increment, divided into prefix and postincrement The values of Boolean and NULL are invalid.	Y = 2 ++ Y (prefix) Y ++ (add later)	Y = 3
--	Descending, divided into descending and descending The values of Boolean and NULL are invalid.	Y = 2 -- Y (minus) Y -- (minus)	Y = 1

For prefix and Postfix, the result after execution is a variable plus 1. The difference is that the returned results are different during execution. See the following two examples:

The Code is as follows:

Var x = 2;
Alert (++ x); // output: 3
Alert (x); // output: 3

Var y = 2;
Alert (y ++); // output: 2
Alert (y); // output: 3

The same is true for decline.

Value assignment operator

The value assignment operator = is used for the value assignment operation. The value assignment operator assigns the value on the right to the variable on the left. Set y = 6. See the following table:

Operator	Example	Equivalent	Calculation Result
=	Y = 6	��	Y = 6
+ =	Y + = 1	Y = y + 1	Y = 7
-=	Y-= 1	Y = Y-1	Y = 5
* =	Y * = 2	Y = y * 2	Y = 12
/=	Y/= 2	Y = y/2	Y = 3
% =	Y % = 4	Y = y % 4	Y = 2

Nested value assignment

Value assignment operators can be nested:

The Code is as follows:

Y = (x = 2) + 5; // result: x = 2, y = 7

Comparison Operators

Operator	Description	Example	Calculation Result
=	Equal	2 = 3	FALSE
===	Constant equals (compare values and types)	2 = 2 2 = "2"	TRUE FALSE
! =	Not equal to or writeable <>	2 = 3	TRUE
>	Greater	2> 3	FALSE
<	Less	2 <3	TRUE
> =	Greater than or equal	2> = 3	FALSE
<=	Less than or equal	2 <= 3	TRUE

Comparison operators can also be used for string comparison.

Ternary Operators

Three elements can be considered as special comparison operators:

The Code is as follows:

(Expr1 )? (Expr2): (expr3)

Syntax explanation: when the value of expr1 is 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); // output: 2

In this example, we determine whether the value of x is equal to 2. If x is equal to 2, the value of y is equal to x (that is, 2), and y is equal to 1.

Prompt

To avoid errors, it is a good idea to enclose the expressions of the ternary operators in parentheses.

Logical operators

Operator	Description	Example	Calculation Result
&&	Logic and (and)	X = 2; Y = 6; X & y> 5	FALSE
|	Logic or (or)	X = 2; Y = 6; X & y> 5	TRUE
!	Non-logical, taking the opposite of Logic	X = 2; Y = 6; ! (X> y)	TRUE

String concatenation operator

The concatenation operator + is used to connect two strings or string variables. Therefore, when this operator is used for strings or string variables, it is not used for addition calculation.

Example:

The Code is as follows:

X = "beijing ";
Y = x + "Hello! "; // Result: y =" beijing hello! "

// To add a space between two strings, insert the space into a string:
Y = x + "Hello! "; // Result: y =" beijing hello! "

When you connect a string to a number (addition), the number is first converted to a string and then connected (added ):

The Code is as follows:

X = 25;
Y = "I am" + x + "years old"; // result: y = "I am 25 years old"