How to set a value of the textarea without id by javascript?

Question

Typically we run javascript code to set any value:

document.getElementById(\'id_name\').value = \"...\";

But I have a page like this:

Answer 1

Modern browsers support the Selectors API (through querySelector), which lets you do this very easily:

document.querySelector("#id_name > .classname > textarea").value = "foo";

For completeness, I should mention that this will operate on the first element that matches the selector (you can also tweak the selector of course). If there is the possibility of having many elements that need to be targeted, you can switch to querySelectorAll and a loop.