5.4 Operators
You will use lots of operators in expressions. Earlier, you used the equal sign (=) as an assignment operator to assign a value to a variable. In the preceding examples with strings, you used the plus symbol (+) to join two strings. An operator generally performs some kind of calculation (operation) or comparison with two values (the value on each side of an operator is called an operand ) to reach a third value. In this lesson, you will see the different types of operators used in JavaScript programming.
Arithmatic Operators:
| Operator | Description | Example | Result |
|---|---|---|---|
| + | Addition | X=2Y=2X+y | 4 |
| – | Substraction | X=5Y=2x-y | 3 |
| * | Multiplication | X=5Y=4X*5 | 20 |
| / | Division | 15/55/2 | 32.5 |
| % | Modulus (division remainder) | 5%210%810%2 | 120 |
| ++ | Increment | X=5X++ | X=6 |
| — | Decrement | X=5x– | X=4 |
<html>
<body>
<script type =”text/javascript”>
<!—
Var two =2
Var ten = 10
Var linebreak = “<br/>”
document write (“two plus ten =”)
result = two+ten
document.write (result)
document.write(linebreak)
document.write(“ten *ten =”)
result = ten*ten
document.write(result)
document.write(linebreak)
document.write (“ten/two =”)
result = ten/two
document.write (result)
// – – >
</script>
</body>
<html>
5.4.2 Assignment Operators
| Operator | Example | Is The Same As |
|---|---|---|
| = | X=y | X=y |
| += | X+=y | X=x+y |
| -= | x-=y | X=x-y |
| *= | X*=y | X=x*y |
| /= | x/=y | X=x/y |
| %= | X%=y | X=x%y |
5.4.3 Comparison Operators
| Operator | Description | Example |
|---|---|---|
| == | Is equal to | 5==8 returns false |
| === | Is equal to (checks for both value and type) | X=5Y=”5” |
| X==y returns trueX==y returns false | ||
| != | Is not equal | 5!=8 returns true |
| > | Is greater than | 5>8 returns false |
| < | Is less than | 5<8 returns true |
| >= | Is greater than or equal to | 5>=8 returns false |
| <= | Is less than or equal to | 5<=8 returns true |
5.4.4 Logical Operator
| Operator | Description | Example |
|---|---|---|
| && | And | X=6Y=3
(x<10&& y>1) returns true |
| II | Or | X=6Y=3
(x== II y==5) returns false |
| ! | not | X=6Y=3
!(x==y) returns true |
5.4.5 String Operator
The string operator concatenates one or more string using + operator
Txt1 = “have”
Txt2 = “a nice”
Txt3 = “day”
Txt4 = txt1+txt2+txt3;
The output of above example would be have a nice day
<html>
<head>
<title>
My script
</title>
</head>
<body>
<script type = “text/javascript”>
Document.write (“<h1> welcome to <br/> JavaScript + “<br/> programming!
<h1>”);
Window.alert (“click here”);
</script>
</body>
</html>
The above javascript program executes and displays following as output. Welcome to JavaScript programming
5.4.6 Conditional Assignment operator
Conditional operator checks a condition and then assigns a value to a variable. The general syntax of the conditional assignment of operator is shown below:
Variable = (condition)? Value1 : Value2;
Here, condition is the logical expression
Value 1 is the value assigned to the variable when the logical expression is true.
Value 2 is the value assigned to the variable when the logical expression is false.
Example code snippet:
String result;
Result = (mark>40)? “pass”:”fail”;
In this example, the value “pass” is assigned when mare is greater than or equal to 40. Other wise “fail” is assigned.
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