[Guide] Basic JS: parseInt using radix. Replace stub with guide (#22456)

Guide for [Basic JavaScript: Use the parseInt Function with a Radix](https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix)

guide/english/certifications/javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix/index.md

@@ -3,8 +3,41 @@ title: Use the parseInt Function with a Radix
 ---
 ## Use the parseInt Function with a Radix
 
-This is a stub. <a href='https://github.com/freecodecamp/guides/tree/master/src/pages/certifications/javascript-algorithms-and-data-structures/basic-javascript/use-the-parseint-function-with-a-radix/index.md' target='_blank' rel='nofollow'>Help our community expand it</a>.
 
-<a href='https://github.com/freecodecamp/guides/blob/master/README.md' target='_blank' rel='nofollow'>This quick style guide will help ensure your pull request gets accepted</a>.
+### Problem explanation:
+_Use `parseInt()` in the `convertToInteger` function so it converts a binary number to an integer and returns it._
+
+#### Hint 1
+If you use a variable to assign the result of `parseInt(str)` to it, remember to return that variable. 
+Otherwise you can just use a `return` statement for your function.
+> _try to solve the problem now_
+> 
+#### Hint 2
+In this exercise you need to "convert" a binary number into a decimal number using the `radix` parameter in order to specify the base on which the input number is represented on.
+> _try to solve the problem now_
+
+## Spoiler alert!
+
+**Solution ahead!**
+
+## Code solution:
+
+```javascript
+function convertToInteger(str) {
+  return parseInt(str, 2);
+}
+convertToInteger("10011");
+```
+·  Run code at [repl.it](https://repl.it/@AdrianSkar/Basic-JS-Use-parseInt-with-radix).
+
+### Code explanation
+- The function takes `str` and returns an integer instead of a string but "understanding" its a binary number instead of a decimal one thanks to the `radix` parameter (2).
+
+
+### Resources
+
+- ["parseInt()" - *MDN JavaScript reference*](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/parseInt)
+- ["Radix" - *Wikipedia*](https://en.wikipedia.org/wiki/Radix)
+
+
 
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