How do I select a DOM element that has multiple classes?

Question

I am trying to select a DOM element that has these classes:

mq-editable-field mq-math-mode mq-field

I have tried using:

document.getElementsByClassName('mq-editable-field mq-math-mode mq-focused')

This is not working, is there another document function I should be using? I am using vanilla javascript.

Answer 1

使用查询选择器：

document.querySelector('.mq-editable-field.mq-math-mode.mq-focused')

Answer 2

you can use querySelector and querySelectorAll for get multiple-element by classes

querySelector method : return the first element within the document which matches a specified CSS selector(s)

let firstElement= document.querySelector('.mq-editable-field.mq-math-mode.mq-focused');

querySelectorAll() method : method returns all the elements within the document which matches the specified CSS selector(s).

let elements = document.querySelectorAll('.mq-editable-field.mq-math-mode.mq-focused');