The module ext.wikilambda.edit/mixins/domUtils.js only exports one function that is called only once in the code.
The module partially takes advantage of jQuery. A call to jQuery('my-selector').first().text('my-text') keeps only the first element matching the selector if any and change the text. If no element matches the selector, there is no error (the call to text() does nothing).
I feel like it can simplify a bit the code. What do you think?