Remove all characters after specific character from right to left

Question

I was trying to implement a function in Node.js that does what the title of this question requires. For example, if the caracters was _

Input

foo_bar_baz

Output

foo_bar

Input

foo_bar_baz_foz

Output

foo_bar_baz

Answer 1

You can use string#substr with string#lastIndexOf to remove pick letter between first character till last occurrence of your char .

 word.substr(0, word.lastIndexOf(char))

 const str = ['foo_bar_baz', 'foo_bar_baz_foz'], char = '_', result = str.map(word => word.substr(0, word.lastIndexOf(char))); console.log(result);

Answer 2

If you want to use regex, you can just do .*(?=_)

 const string = "foo_bar_baz"; console.log(string.match(/.*(?=_)/)[0]);

Answer 3

You don't need regex for this, just split the data by the identifier and remove the last item from the array and rejoin the array by the identifier

 const test = "foo_bar_baz_foz"; function removeLR(string, identifier) { const arr = string.split(identifier); arr.splice(arr.length - 1, 1); return arr.join(identifier); } console.log(removeLR(test, "_"))