[FEATURE] switch to string constants in JS

[XhmikosR]

I recently did this on Bootstrap itself for both our master and v4-dev branches.

• Switch to strings constants. twbs/bootstrap#30358
• Switch to string constants. twbs/bootstrap#30490

@REJack As you can see the results are pretty big. 🙂

Would be nice if you made the change on AdminLTE itself.

PS. we have released a v4.5.0 upstream, but there are a couple of regressions we have to fix. After v4.5.1 is out, you should definitely update to that.

[REJack]

That's a really nice idea, I had also the idea to replace the constants before. But I saw no benefit from it, but now I see it reduces the JS file size 😄. I'll change while the v3.1 development.

[XhmikosR]

I'll take a stab at it after the current PRs are sorted. Have you thought about adding bundlewatch to monitor the sizes?