How to use replace function for multiple occurrences.

Question

Hello,

I have a string in syncfusion rich text box which is  "This is a good forum" 

So in rich text box it is interpreted as  

 

MyString = <p><span style="text-decoration: underline;">This</span> is a good <span style="text-decoration: underline;">forum</span></p> 

 

Now, i want to use replace function in angular 6.

I want to replace  <span style="text-decoration: underline;">  with <u>

In MyString its coming 2 times but when i use replace function it replaces only 1st occurrence.

and 2nd occurrence remains as it is.

So how can i replace all occurrences.

FormattedDesc =MyString.replace('<span style="text-decoration: underline;">', '<u>');

Please any help would be appreciated. Thank you.