chrome devtools: variable accessors



~2 min read


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In the Ember DevTools, there’s a convenience that nearly every variable can be bound to a magic $E.

These elements are then sent to the console and available for further inspection.

I am working less within Ember these days, which is why I was so glad when some colleagues shared methods by which I could emulate this behavior using some native browser “magic.”

There are two different solutions:

  1. Store an element as a global variable
  2. Selector/function shorthand

Storing Elements As Global Variables

This is the most similar situation to what Ember provides.

When inspecting a page’s markup, by right clicking on the desired element, you can select “Store as global variable.”

And, like Ember’s DevTools, this variable is then made available for interrogation in the console:

Selector / Function Shorthand

Instead of writing document.querySelector (or the many variations), many browsers now have built-in shorthand. Here’s how my friend described them:

  • $ is essentially document.querySelector i.e. $('body') returns <body>.
  • $$ is essentially document.querySelectorAll i.e. $('head, body') returns , <body.
  • $0-4 is the nth last element you’ve selected in the elements panel. i.e. if you select a <div> and then a <button>, $0 is the <button> and $1 is the <div>
  • $_ is the result of the last expression you executed in the console*. i.e. if you run 1+2, $_ will be 3. I find this particularly useful for simple math calculations (1 + 2, $_ + 3, $_ + 4, $_ / 4, etc)
  • There’s an 👀 button in Chrome/Edge to create live expressions that rerun automatically. I find them particularly useful for tracking document.activeElement which is the element that currently has focus.
  • Live expressions will overwrite $_, so be sure to disable any live expressions if you want to use $_.

Wrap up

That’s all for now. Just a few niceties built into Chrome!

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