LoadJS – A tiny async loader for modern browsers (710 bytes)

<a href="https:&#x2F;&#x2F;github.com&#x2F;walmartlabs&#x2F;little-loader" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;walmartlabs&#x2F;little-loader</a> is smaller (519 bytes min+gzipped), supports IE8, and fires either on script load or on error synchronoulsy (so that globals won&#x27;t be overwritten by code that runs between script loading and the callback firing). The thing is tested on SauceLabs down to IE8.<p>The drawback is a lower level API, and it is JS only. AFAIK loading CSS consistently cross browser is also a mine field if you want consistent error handling.<p><pre><code> window._lload(&quot;http:&#x2F;&#x2F;example.com&#x2F;foo.js&quot;, function (err) { &#x2F;&#x2F; `err` is script load error. &#x2F;&#x2F; otherwise, foo.js is loaded! }&#x2F;*, [optional context (`this`) variable here] *&#x2F;);</code></pre>

This looks like the perfect case for using Promises...<p><pre><code> loadjs(&#x27;foobar&#x27;).then(() =&gt; { &#x2F;&#x2F; foobar.js loaded }); </code></pre> And then with the newer spec:<p><pre><code> await loadjs(&#x27;foobar&#x27;); &#x2F;&#x2F; foobar.js loaded </code></pre> Such a pity that instead it uses a proprietary format.<p>Edit: you could still add all other nice things without compromising the main thing, for example to add a &quot;before&quot;:<p><pre><code> loadjs.before(fnA).before(fnB).load(&#x27;foobar&#x27;).then(() =&gt; {});</code></pre>

I made a similar thing that is supposed to be vaguely require.js compatible in 541-588 bytes, depending on enabled features [1]. Not production ready :).<p>[1] <a href="https:&#x2F;&#x2F;github.com&#x2F;gliptic&#x2F;hypjs&#x2F;blob&#x2F;master&#x2F;src&#x2F;amd.ts" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;gliptic&#x2F;hypjs&#x2F;blob&#x2F;master&#x2F;src&#x2F;amd.ts</a>

<a href="https:&#x2F;&#x2F;github.com&#x2F;QubitProducts&#x2F;micro-amd" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;QubitProducts&#x2F;micro-amd</a> is another project with similar goals. Its pretty small, amd compliant and battle tested

Seems handy for the callbacks, but will this be as useful once http2 is the default?

back in the day you just did script src... none of this bullshit

Wow. This makes Labjs, which has been my preferred loader, seem heavy.

That&#x27;s cool. Would this help with my page speed score that almost is always like a D- for stuff related to async&#x2F;css&#x2F;js and &#x27;deferred&#x27; loading?

It seems to lack the handling of timeouts, which is necessary in these async days.