Q:

Universal String selector for Javascript?

I have something like
x.getElementById("foo" + rowIndex);

There are a couple of cases that have some other string before the "foo" in the ID,  and my question is if there are any replacements (like the "%" in SQL) that I could use to add something else to the "foo" like
x.getElementById("%foo" + rowIndex);

A:

If you use querySelector instead of getElementById, you can pass a selector string that selects an ID which ends with the substring you want, for example:
x.querySelector('[id$="foo' + rowIndex + '"]');

const rowIndex = 3;
console.log(document.querySelector('[id$="foo' + rowIndex + '"]'));
<div id="barfoo3">text</div>

(of course, if you want to select all elements whose ID ends with that, use querySelectorAll instead of querySelector)
That said, note that such dynamic IDs are somewhat of a code smell - you might consider if there are more elegant alternative methods.

