# JavaScript | parseInt() with Examples

The parseInt() is an inbuilt function in JavaScript which is used to accept the string and convert it into an integer. It actually returns an integer of the specified radix(base) which is accepted as second parameter of the parseInt() function. If the string does not contain a numeric value then it returns NaN i.e, not a number.
Syntax:

`parseInt(Value, radix)`

Parameters: It accepts two parameter which are specified below-

• Value: “Value” contains a string which is converted to an integer.
• radix: This parameter represents the radix or base to be used and it is optional.
• Return value: It returns a number and if the first character can’t be converted to a number then the function returns NaN. It actually returns a number parsed up to that point where it encounters a character which is not a number in the specified radix(base).
Example:

```Input: var n = parseInt("2018@geeksforgeeks");
Output: n = 2018
now n contains 2018 as '@' is not a Number
and parsing stops at that point,further characters are ignored.
Input: var a = parseInt("1000");
Output: a = 1000(Number)
```

JavaScript to show the working of parseInt() function:

Code #1:

 ` ` ` ` ` ` `    `` ` ` `  ` ` `                     `

Output:

```parseInt("100") = 100
parseInt("2018@geeksforgeeks") = 2018
parseInt("geeksforgeeks@2018") = NaN
parseInt("3.14") = 3
parseInt("21 7 2018") = 21```

Code #2:
If the radix is not mentioned in parseInt() function and starting of string contain “0x” than it treated as hexadecimal value. By default radix is 10 (decimal). Note that in line 11 there is ‘8’ which is a character that is not defined in radix 8 numeral system therefore it returns NaN.

 ` ` ` ` `    `` ` `        `` ` `     `  `    `` ` `                                 `

Output:

```parseInt("100",10) = 100
parseInt("8",8) = NaN
parseInt("15",8) = 13
parseInt("16",16) = 22
parseInt(" 100 ") = 100
parseInt("0x16") = 22```

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