JavaScript operators mainly include:
Arithmetic operators
Assignment operators
Comparison operators
Ternary operator
Logical operator
String concatenation operator
Arithmetic operators
##Operators
Description Operator ##+ Add y = 2+1 y = 3
- Subtract y = 2-1 y = 1
* Multiply y = 2*3 y = 6
/ Division, the return result is a floating point type y = 6/3 y = 2
% Find remainder, the return result is a floating point type Requires two operations The numbers are all integers y = 6%4 y = 2
++ Increasingly, divided into pre-add and post-add. It will be invalid for Boolean values and NULL y = 2 ++y (pre-add) y++ (post-add) Add) y=3
##For pre-add and post-add, the result after execution is the variable plus 1. The difference is that the return result is different during execution. Please refer to the following two examples:
var x = 2;
alert(++x); //Output: 3
alert(x); //Output: 3
var y = 2;
alert(y++); / /Output: 2
alert(y); //Output: 3
##Assignment operator
Assignment operator = is used for assignment operations. 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
Example is equivalent to
Operation result
##= y = 6 empty 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
##Comparison operations Symbol
Operator Explanation Example Operation result
== Equal to 2 == 3 FALSE
=== Constantly equal (both values and types must be compared) ( 2 === 2 TRUE ) ( 2 === "2" FALSE )
!= Not equal, it can also be written as <> 2 == 3 TRUE > Greater than 2 > 3 FALSE < Less than 2 < 3 TRUE >= Greater than or equal to 2 >= 3 FALSE <= Less than or equal to 2 < ;= 3 TRUE
ternary operator
Ternary operator can be regarded as a special comparison Operator: (expr1) ? (expr2) : (expr3)
Syntax explanation: When expr1 evaluates to TRUE, the value of the entire expression is expr2, otherwise it is expr3 . Example:x = 2;y = (x == 2) ? x : 1;
alert(y); //Output: 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.
Logical Operators
Operator Explanation Example Operation result
&& Logical AND (and) x = 2; y = 6; x && y > 5 FALSE
|| Logical OR (or) x = 2; y = 6; The opposite of x = 2; y = 6; !(x > y) TRUE
##String concatenation operator The connection operator + is mainly used to connect two strings or string variables. Therefore, when you use this operator on strings or string variables, you are not adding them.
Example:x = "beijing";
y = x + "Hello!"; //Result: y = "Hello beijing!"// To add spaces between two strings, you need to insert spaces into a string:
y = x + "Hello!"; //Result: y = "beijing you OK! "
When performing the concatenation (addition) operation on strings and numbers, the numbers will be converted into strings and then concatenated (added):
x = 25;
y = "I am this year" + x + "years old"; //Result: y = "I am 25 years old this year"
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>php中文网(php.cn)</title>
</head>
<body>
<button onclick="myFunction()">点击这里</button>
<p id="demo"></p>
<script>
function myFunction()
{
txt1="What a very";
txt2="nice day";
txt3=txt1+txt2;
document.getElementById("demo").innerHTML=txt3;
}
</script>
</body>
</html>
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