# JavaScript: Convert a binary number to a decimal number

## JavaScript Math: Exercise-2 with Solution

Write a JavaScript function to convert a binary number to a decimal number.

Test Data: console.log(bin_to_dec('110011')); console.log(bin_to_dec('100')); 51 4

**Visual Presentation:**

**Sample Solution:**

**JavaScript Code:**

```
// Define a function named bin_to_dec that takes a binary string as input and converts it to decimal.
function bin_to_dec(bstr) {
// Convert the binary string to a decimal integer using parseInt, removing any non-binary characters.
return parseInt((bstr + '').replace(/[^01]/gi, ''), 2);
}
// Output the decimal conversion of the binary string '110011' to the console.
console.log(bin_to_dec('110011'));
// Output the decimal conversion of the binary string '100' to the console.
console.log(bin_to_dec('100'));
```

Output:

51 4

**Explanation:**

In the exercise above,

- The code defines a function named "bin_to_dec()" which takes a binary string (bstr) as input.
- Inside the function, it converts the binary string to a decimal integer using the "parseInt()" function. The regular expression (/[^01]/gi, '') is used with "replace()" to remove any characters that are not '0' or '1' from the binary string.
- The "parseInt()" function is then used to convert the cleaned binary string to a decimal integer, specifying base 2 (binary) as the second argument.
- The function returns the decimal and integer representation of the binary string.

**Flowchart:**

**Live Demo: **

See the Pen javascript-math-exercise-2 by w3resource (@w3resource) on CodePen.

**Improve this sample solution and post your code through Disqus.**

**Previous:** Write a JavaScript function to convert a number from one base to another.

**Next:** Write a JavaScript function to convert a decimal number to binary, hexadecimal or octal number.

**What is the difficulty level of this exercise?**

Test your Programming skills with w3resource's quiz.

**It will be nice if you may share this link in any developer community or anywhere else, from where other developers may find this content. Thanks.**

https://www.w3resource.com/javascript-exercises/javascript-math-exercise-2.php

**Weekly Trends and Language Statistics**- Weekly Trends and Language Statistics