You don't need all that crazy jQuery! It's simple enough!

 
 var message = "Hello World",
 messageEl = document.createTextNode( message );
 
 out.appendChild( messageEl );

<img src="https://i.sstatic.net/V6KuG.gif" width="480" height="1"><sup><sup><sup><sup><sup>**[`  [ run with user script ]  `](http://scripts.jeremybanks.ca/run-stackexchange-code-0.0.user.js)**</sup></sup></sup>

---

 $( out ).append( $( "<p>Hello World</p>" ) );

<img src="https://i.sstatic.net/V6KuG.gif" width="480" height="1"><sup><sup><sup><sup>**[`  [ run with user script ]  `](http://scripts.jeremybanks.ca/run-stackexchange-code-0.0.user.js)**</sup></sup></sup></sup>

?

---

 var message = "Hello World",
 messageEl = document.createElement( "p" );
 
 messageEl.textContent = message;
 out.appendChild( messageEl );

<img src="https://i.sstatic.net/V6KuG.gif" width="480" height="1"><sup><sup><sup><sup><sup>**[`  [ run with user script ]  `](http://scripts.jeremybanks.ca/run-stackexchange-code-0.0.user.js)**</sup></sup></sup></sup></sup>

!

---

Want to be able to run your code like that? Just add this line below a code block:

> `<img src="https://i.sstatic.net/V6KuG.gif" width="480" height="1"><sup><sup><sup><sup>**[`  [ run with user script ]  `](http://scripts.jeremybanks.ca/run-stackexchange-code-0.0.user.js)**</sup></sup></sup></sup></sup>`


Your code's wrapped in a functon under the global context, only given the `out` element as an argument.


---

 atest( "TO FAIL | return false", function () { return false; } );
 atest( "TO FAIL | do nothing", function () { } );
 atest( "TO FAIL | error", function () { throw new Error; } );
 
 atest( "TO FAIL | don't let more than 2 seconds pass", function ( assert, pass, toCleanUp ) {
 var start = new Date;
 
 return function poll () {
 assert( ((new Date) - start) < 2000, "two seconds must not pass" );
 return poll;
 }
 } );
 
 atest( "return true", function () { return true; } );
 
 atest( "Count to 10 Over 1 Second", function ( assert, pass, toCleanUp ) {
 var val = 0,
 incInterval = setInterval( incVal, 100 );
 
 function incVal () {
 val += 1;
 }
 
 toCleanUp(function () {
 clearInterval( incInterval );
 })
 
 return function poll () {
 return ( val > 10 ) ? true : poll;
 };
 });
 
 atest( "Load /", function ( assert, pass, toCleanUp ) {
 jQuery.ajax( "/" ).done(function ( data ) {
 pass( "Loaded " + data.length + " chars." );
 });
 });
 
 atest( "Adding even integers doesn't produce an odd one", function ( assert, pass, toCleanUp ) {
 for (var n = -10000; n < 10000; n += 2) {
 assert( n % 2 === 0, "" + n + " is not a multiple of two." )
 }
 pass();
 });
 
 /*\
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 
 atest( name, body( assert, pass, toCleanUp ) ); *
 Declares an test with the specifed name and body. It will be *
 run synconously with other tests defined syncronously with it. *
 *
 runaTest( body( assert, pass, toCleanUp ) ); *
 Executes a test body and returns a promise of the result. *
 *
 A test body can return true to pass, false to fail or a function *
 to continue to it asyncronously. This happens with a delay, so it *
 can be used to poll some state. *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 
 \*/
 
 runaTest.timeout = 5000;
 runaTest.tickDelay = 100;
 atest.cooldown = 250;
 
 function atest ( name, body ) {
 if ( !atest.buffer ) {
 atest.buffer = [];
 setTimeout( triggerTests, 0 );
 }
 
 atest.buffer.push( [ name, body ] );
 
 function triggerTests () {
 var buffer = atest.buffer,
 i = 0;
 
 delete atest.buffer;
 triggerNext();
 
 function triggerNext () {
 if ( i < buffer.length ) {
 var name = buffer[ i ][ 0 ],
 body = buffer[ i ][ 1 ],
 testRun = runaTest( body );
 
 testRun.then(function passed () {
 $("<p/>").text( [ "pass [" + name + "]" ].concat( [].slice.call( arguments ) ).join(" - ") ).appendTo(out);
 }, function failed () {
 $("<p/>").text( [ "FAIL [" + name + "]" ].concat( [].slice.call( arguments ) ).join(" - ") ).css("color", "red").appendTo(out);
 });
 
 testRun.always(function () {
 setTimeout( triggerNext, atest.cooldown );
 });
 
 ++i;
 }
 }
 }
 }
 
 function runaTest ( body ) {
 var result = new jQuery.Deferred,
 tickInterval = setInterval( tick, runaTest.tickDelay ),
 timeoutTimeout = setTimeout( result.reject, runaTest.timeout, "Timeout" ),
 active = body;
 
 return result.promise();
 
 function assert ( condition, msg ) {
 if ( !condition ) {
 var failArgs = [ "Assertion failed" ].concat( [].slice.call( arguments, 1 ) );
 result.reject.apply( result, failArgs ) ;
 }
 }
 
 function tick () {
 if ( result.state() === "pending" ) {
 if ( typeof active === "function" ) {
 try {
 active = active.call( result, assert, result.resolve, result.always );
 } catch ( ex ) {
 result.reject( "Uncaught exception", ex );
 $("<p/>").text(ex.stack).appendTo(out);
 }
 } else if ( active === true ) {
 result.resolve();
 } else if ( active === false ) {
 result.reject();
 }
 } else {
 clearInterval( tickInterval );
 }
 }
 }

<img src="https://i.sstatic.net/V6KuG.gif" width="480" height="1"><sup><sup><sup><sup>**[ ` [ run with user script ] ` ](http://scripts.jeremybanks.ca/run-stackexchange-code-0.0.user.js)**</sup></sup></sup></sup></sup>

---

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