Type decoration are not needed like in Javascript variables like int, Stings, etc. It auto get type by variable value. String is define single( ‘ ‘ ) or double (” “) quote. JavaScript string as the number is nothing just you can define numbers value only inside the quotes then it will become strings.
Define JavaScript string as a number
Let’s define a number in double quote as a string. And then check if its string or not?
<!DOCTYPE html>
<html>
<head>
<script>
var str_num1 = "10";
var str_num2 = '20';
alert(typeof str_num1 === 'string')
</script>
</head>
</html>Output:
How to change string as number to Number
As we learned about JS string as number now let’s convert it into number(int/integer) type data.
We are doing examples with parseint() and Number() Function.
After converted will check its number or not using Number.isInteger() method.
1. JavaScript parseInt() Function
The parseInt() function parses a string and returns an integer.
<!DOCTYPE html>
<html>
<head>
<script>
var str_num1 = "10";
var a = parseInt(str_num1)
alert(Number.isInteger(a))
</script>
</head>
</html>Output: true
2. JavaScript Number() Function
Convert different object values to their numbers:
Number('123') // returns the number 123
Number('123') === 123 // true
Number("unicorn") // NaN
Number(undefined) // NaNDo comment if you have any doubts and suggestion on this tutorial.
Note: The All JS Examples codes are tested on the Safari browser (Version 12.0.2) and Chrome.
OS: macOS 10.14 Mojave
Code: HTML 5 Version