variable : A variable is a user defined name which is used to store constant values in it. Variable is a name which is given to memory location.
In Javascript variable Declaration to Datatypes is not mandatory.
Data Types (Type of Constant Values )
1. Number (int – 4 bytes , float – 8 bytes , Double 16 bytes)
2. String ('*', 'abc' or "abc")
3. Boolean (True or False)
Data Type Variables:
Example
Var a;
a = 'W3C';
---(or)---
Var a = 'W3C';
---(or)---
a = 'W3C';
Points to remember for naming the variables
String
1) Use \ when using a quotes " or Apostrophe inside a string.
Ex :
"Hai \" I am Robert"
Note : \ indicates to browser that coming char is not a special char.
2) \n is for next line
Ex :
A = "This is an \n example"
A = "This is an\\n example"
Boolean
Boolean a = true;
Boolean a = false;
Note : don't use quotes like 'true'
Example:
<script type="text/javascript">
document.write("<h2>Welcome To \"JS\"</h2>");
a=123;
b='hello';
c=5>3;
document.write("a=" + a + "<br/>b=" + b + "<br/>c=" + c);
/* js comment */
x=6; y=4;
document.write("<br/>sum=" + (x+y));
document.write("<br/>Type of b is " + typeof(b));
per=57.86948775467656;
document.write("<br/>Per=" + per.toFixed(2)); // per=57.87
document.write("<br/>Per=" + per.toFixed(0)); // per=58
document.write("<br/>Per=" + Math.round(per)); // per=58
document.write("<br/>Per=" + Math.floor(per)); // per=57
document.write("<br/>Per=" + Math.ceil(per)); // per=58
</script>
To get the data type of var
a = 10;
b = typeof(a); ( it is Expression and function )
document.write(b);
Example-2
<html>
<head>
<script>
a = 10;
b = typeof(a);
document.write( b );
</script>
</head>
<body>
</body>
</html>
Note : typeof() is a function as well as expression.
In Javascript variable Declaration to Datatypes is not mandatory.
Data Types (Type of Constant Values )
1. Number (int – 4 bytes , float – 8 bytes , Double 16 bytes)
2. String ('*', 'abc' or "abc")
3. Boolean (True or False)
Data Type Variables:
Example
Var a;
a = 'W3C';
---(or)---
Var a = 'W3C';
---(or)---
a = 'W3C';
Points to remember for naming the variables
- First char of var name must be in A-Z (or) a-z (or) _ (underscore).
- Spaces are not allowed.
- Avoid built in functions and reserve words as variable names.
String
1) Use \ when using a quotes " or Apostrophe inside a string.
Ex :
"Hai \" I am Robert"
Note : \ indicates to browser that coming char is not a special char.
2) \n is for next line
Ex :
A = "This is an \n example"
A = "This is an\\n example"
Boolean
Boolean a = true;
Boolean a = false;
Note : don't use quotes like 'true'
Example:
<script type="text/javascript">
document.write("<h2>Welcome To \"JS\"</h2>");
a=123;
b='hello';
c=5>3;
document.write("a=" + a + "<br/>b=" + b + "<br/>c=" + c);
/* js comment */
x=6; y=4;
document.write("<br/>sum=" + (x+y));
document.write("<br/>Type of b is " + typeof(b));
per=57.86948775467656;
document.write("<br/>Per=" + per.toFixed(2)); // per=57.87
document.write("<br/>Per=" + per.toFixed(0)); // per=58
document.write("<br/>Per=" + Math.round(per)); // per=58
document.write("<br/>Per=" + Math.floor(per)); // per=57
document.write("<br/>Per=" + Math.ceil(per)); // per=58
</script>
To get the data type of var
a = 10;
b = typeof(a); ( it is Expression and function )
document.write(b);
Example-2
<html>
<head>
<script>
a = 10;
b = typeof(a);
document.write( b );
</script>
</head>
<body>
</body>
</html>
Note : typeof() is a function as well as expression.
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