How to strip non-digit characters from an id attribute with JavaScript

Question

I am reading the id from a list tag an add it to a pre tag like this:

$('pre').each(function() {
  $(this).attr('id', $(this).closest('li').attr('id'));
});

for example, the list tag has this id:

<li id="Comment_123">

For the pre tag, I want to remove the first 8 characters from the id; so the pre tag should become this id:

<pre id="123">  

How can I achieve this with the code I already have?

Answer 1

如果您知道所有ID具有相同的结构，则可以删除_（含）之前的内容。

var id = $(this).closest('li').attr('id').split('_').pop();

Answer 2

If it's set at the first 8 chars, then use substring

var id = $(this).closest('li').attr('id');
var shortened = id.substring(8, id.length);

$(this).attr('id', shortened);

Answer 3

If you want to strip everything except digits, you could use .replace(/\\D/g, '') :

$('pre').each(function () {
  this.id = $(this).closest('li').attr('id').replace(/\D/g, '');
});

• \\D - Matches any non-digit character .
• g is a global flag to match all occurrences.

In other words, all occurrences of any non-digit character(s) are replaced with an empty string, '' .