How to slice string from the end in JavaScript?

Question

I have a list of binary values as strings with different lengths, however I need to slice off the last 18 characters from each value. So in the examples below, the bold is what needs to be kept.

11001000000000000001010

110000000001101011100

What would be the way to do this using JavaScript?

what exactly about [`String.prototype.slice`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/slice) do you not understand? — Hamms, Feb 17 '17 at 23:14
What do you want to do if the binary value is less than 18 characters — nivas, Feb 17 '17 at 23:19
@nivas none of the values I have are less than 18 so it won't be an issue. — Gazz, Feb 17 '17 at 23:21
You could use `str.substr(0, str.length - 18);` which is clearer! — ibrahim mahrir, Feb 17 '17 at 23:27

kind user · Accepted Answer · 2017-02-18T10:36:44.707

You have to use negative index in String.prototype.slice() function.

using negative index as first argument returns the sliced string to the 6 elements counting from the end of the string.

var example = "javascript";
console.log(example.slice(-6));

using negative index as the second argument returns the sliced string from 0 to the 6th element counting from the end. It's opposite to the first method.

var example = "javascript";

console.log(example.slice(0, -6));

In your particular case, you have to use the second method.

console.log('11001000000000000001010'.slice(0, -18));

console.log('110000000001101011100'.slice(0, -18));

If you want to read more about that function, visit: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/slice

If you're still interessted http://meta.stackoverflow.com/questions/344581/so-should-force-downvoters-to-leave-a-comment — ibrahim mahrir, Feb 26 '17 at 02:23

How to slice string from the end in JavaScript?

1 Answers1

Linked