The assignment operator, =, is used to assign values to JavaScript variables, as shown in the first two lines of the following code.
The arithmetic operator, +, is used to add values together, as shown in the last line of the following code.
y = 5;z = 2;x = y+z;
The value of x, after the execution of the preceding statements is 7.
JavaScript Arithmetic Operators
Arithmetic operators are used to perform arithmetic between variables and/or values.
Given that y = 5, the following table explains the arithmetic operators.
|
Operator
|
Description
|
Example
|
Result
|
|
+
|
Addition
|
x = y+2
|
7
|
|
-
|
Substraction
|
x=y-2
|
3
|
|
*
|
Multiplications
|
X=y*2
|
10
|
|
/
|
Division
|
X=y/2
|
2.5
|
|
%
|
Modulus
|
X=y%2
|
1
|
|
++
|
Increment
|
X=++y
|
6
|
|
--
|
Decrement
|
X=--y
|
4
|
JavaScript Assignment Operators
Assignment operators are used to assign values to JavaScript variables.
Given that x = 10 and y = 5, the following table explains the assignment operators:
|
Operator
|
Example
|
Same As
|
Result
|
|
+
|
X=y
|
|
X=5
|
|
+=
|
X+=y
|
X=x+y
|
X=15
|
|
-=
|
x-=y
|
X=x-y
|
X=5
|
|
/=
|
X/=y
|
X=x/y
|
X=2
|
|
%=
|
X%=y
|
X=x%y
|
X=0
|
|
*=
|
X*=y
|
X=x*y
|
X=50
|
The + Operator Used on Strings
The + operator also can be used to concatenate string variables or text values together. To concatenate two or more string variables together, use the + operator:
txt1="What a very";txt2="nice day";txt3=txt1+txt2;
After the execution of the preceding statements, the variable txt3 contains “What a verynice day”.
To add a space between the two strings, insert a space into one of the strings:
txt1="What a very ";txt2="nice day";txt3=txt1+txt2;
Or insert a space into the expression:
txt1="What a very";txt2="nice day";txt3=txt1+" "+txt2;
After the execution of the preceding statements, the variable txt3 contains:
“What a very nice day”
Adding Strings and Numbers
The rule is as follows:
If you add a number and a string, the result will be a string!
<html><body><script type="text/javascript">x=5+5;document.write(x);document.write("<br />");x="5"+"5";document.write(x);document.write("<br />");x=5+"5";document.write(x);document.write("<br />");x="5"+5;document.write(x);document.write("<br />");</script><p>The rule is: If you add a number and a string, the result will be a string.</p></body></html>
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