Regex last space remover pattern

I have a rich text editor. It generates HTML output. I want to remove last space between i and strong tags.
For example;

Input:

<strong>Hello World </strong>

Expected Output:

<strong>Hello World</strong>

Input:

<strong>Hello World <i>Hello Planet </i> </strong>

Expected Output:

<strong>Hello World <i>Hello Planet</i></strong>

>Solution :

/ (<\/i>|<\/strong>)/g should be replaced with ‘$1’ as shown below:

var str = '<strong>Hello World <i>Hello Planet </i> </strong>';
var patt = / (<\/i>|<\/strong>)/g;
console.log(str.replace(patt, '$1'));
// Produces: '<strong>Hello World <i>Hello Planet</i></strong>'