In previous article, I mentioned Parse CSV file data into Array Using Javascript but in this article, I have mentioned how we can convert string to number (integer) in javascript using various possible ways.

### 1. Using `parseInt()` method

The parseInt() function parses a string argument and returns an integer, it takes a String as a first argument, and a base to which that String will be converted to.

This method always returns an integer.

Syntax:

``parseInt(string, radix)``

Example to convert string to number

``var number = parseInt("10");``

But there is a problem. If you try to convert "010" using parseInt function, it detects as octal number, and will return number 8, so therefore you should pass radix when using parseInt()

• No prefix - If there isn't a prefix, the radix is 10 (decimal).
• 0 - If the prefix is 0, then the radix is 8 (octal). Though, this feature is deprecated.
• 0x - If the prefix is 0x, then the radix is 16 (hexadecimal).

Example:

``````let str = '112';
let floatStr = '112.56';
let binaryStr = '7';
let nanStr = 'hello';

parseInt(str);       // 112
parseInt(floatStr);    // 112
parseInt(binaryStr, 2); // 111 (Binary)
parseInt(nanStr);    // NaN (Not a Number)``````

### 2. Using `Number()`

The `Number()` function accepts a string parameter and converts it to an integer or floating point number, or returns NaN (Not a Number) if the input value doesn't represent a number.

Example:

``var x = Number("1000");``

Note: Note that `Number('')` returns 0, even though most people wouldn't consider the empty string to represent a valid number.

So, before passing string to Number, you can check if it is number using isNAN() function.

### 3. Multiply by 1

You can multiply string value by 1 to convert it into Number.

This method is considered as fastest method to convert string to number using Javascript.

``````let str = '200';
let fltStr = '200.11';
let nanStr = 'hello';

str * 1;      // 200
fltStr * 1;   // 200.11
nanStr * 1;   // NaN
'1000' * 1;   // 1000
'202.15' * 1; // 202.15``````

### 4. Using `.parseFloat()`

The `parseFloat()` function parses an argument (converting it to a string first if needed) and returns a floating point number.

Syntax:

``````parseFloat(string)
``````

In the following all examples, parseFloat() returns 3.14

``````parseFloat(3.14);
parseFloat('3.14');
parseFloat('  3.14  ');
parseFloat('314e-2');
parseFloat('0.0314E+2');``````

but this one return NAN

``````parseFloat('HH2');
``````

### 5. Using Unary plus (+)

Unary operators work on single operands. The Unary (+) operator is no different, and it precedes it's operand.

The unary + operator converts its operand to Number type.

Example:

``````let str = '200';
let fltStr = '200.21';
let nanStr = 'hello';

+str    // 200
+fltStr // 200.21
+nanStr // NaN
+'1000' // 2000
+10.25  // 20.25``````

While using Unary plus (+) operator easily converts string to number in Javascript, it is advised not to use it, since it doesn't make code more readable.

### 6. Using `Math.Floor()`

The Math.floor() function returns the largest integer less than or equal to a given number, but it can also accept string value and convert it to integer by rounding down to the lowest whole number, using Javascript.

Example:

``````Math.round('121')// 121
Math.round('12.5') // 12
Math.round('123abc')// NaN
Math.floor('5.05') // 5``````

You can also use `Math.ceil()` and `Math.round()` in similar way like above, to convert string to int in Javascript.

That's it, hope it helps.

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