You can convert string to int in Javascript using a parseint() function, but before the start, you must new about how javascript represent strings and integer. The parseInt() is an inbuilt function in JavaScript used to convert a string into an integer.
Below code of basic int and strings declaration in JS:-
int -> var num1 = 20;
string -> var num2 = '20';
Now let’s see Javascript parseint() function
Syntax
A syntax for how string to int in JavaScript.
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parseInt(Value, radix) |
parseInt function accept two parameters:- Value and radix
Parameters
Value: Pass the string which will converted to an integer.
radix: This is an optional parameter and represents the radix or base to be used.
Return value:
The JS parseInt() function parses a string and returns an integer. But if it can’t convert first character of string then it will return “NaN”.
Need of Convert string to int javascript
At starting we see 2 type of data declaration in Javascript. Now see what are the problem and where we needed to convert a string to int:-
If you have to the comparison of the two variables, it would fail because they’re two different types of objects. Let’s see the problem in the example code.
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<!DOCTYPE html> <html> <head> <script> var num1 = 20; var num2 = '20'; if (num1 === num2) { console.log(true); } else { console.log(false); } </script> </head> <body> </body> </html> |
Output:
Let’s See the JavaScript parseint() function Example
In the example, we are passing two arguments. The first argument is the string and the second argument is called radix
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<script> var num1 = 20; var num2 = '20'; var newNum = parseInt(num2, 10); // returns 42 if (num1 === newNum) { console.log(true); } else { console.log(false); } </script> |
Output: In output you will see result is “true“.
Step to see console log:- Chrome and Safari browser’s
- Right-click on web page -> select inspect (inspect element for Safari)
- A bottom navigation window will open select -> Console option.
Browser Compatibility javascript string to int parseint() function
Answer: All three methods work in all modern browsers, and IE6 and up.
Question: What if a string argument is a combination of char and number?
Answer: There are many cases:-
- If pass only text -> Function will return
NaN, an acronym for “Not a Number.” - If pass with text-number combination-> Return value will
NaN. - Last if number-text combination -> Will return decimal values.
Code:
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var num1 = 'abc'; var num2 = 'pp20'; var num3 = '20pp'; var newNum1 = parseInt(num1, 10); var newNum2 = parseInt(num2, 10); var newNum3 = parseInt(num3, 10); console.log(newNum1); // NaN console.log(newNum2); // NaN console.log(newNum3); // 20 |
Do comment if you have any doubts and suggestions on this tutorial.
Note: The How to convert String number value to int in JavaScript Examples are tested on Safari browser (Version 12.0.2) and Chrome.
OS: macOS 10.14 Mojave
Code: HTML 5 Version
Degree in Computer Science and Engineer: App Developer and has multiple Programming languages experience. Enthusiasm for technology & like learning technical.