Wednesday, June 16th, 2021 code javascript techniques • 252w

 So we have the requestAnimationFrame, you pass a function and it called after a very specific while (irrelevant to the following).

Now lets see the basic structure:

function loop() {
    update()
    requestAnimationFrame(loop)
}
loop()

Ok now lets wrap the function and call it without calling it by name:

(function loop() {
    update()
    requestAnimationFrame(loop)
})()

Is there any way to remove the name of function and still pass it? There is a magical object called arguments which appears out of nothing every time a function is executed. And the member that we need is arguments.callee which is self reference to the function being executed. So we get rid of the name:

(function () {
    update()
    requestAnimationFrame(arguments.callee)
})()

And of course to maximize the coolness we put in a single line:

(function() { update(); requestAnimationFrame(arguments.callee) })()

Ok, this very cool, but is it worth it? Let's analyze what this code succeeds to do:

1. Confuses the next reader of the code.
2. Confuses also the 2nd reader.
3. Confuses also the 3rd reader.
...
N. Confuses also the N-th reader.

So you have to choose what is cooler: confusing no people or confusing up to infinite people? Comment below, like and subscribe.



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Sunday, July 21st, 2019 code javascript techniques • 158w
So, I just wanted a simple thing... I had a static html page where I wanted to put some things in dynamically: a simple date at the start and an extended date in the middle of the text. (Also what is server side?)

Pure elegant javascript:

.... <span data-value="simple"></span> ....

<script>

var data = {
    simple: gen_simple(),
    ....
}

for (var i of document.querySelectorAll('[data-value]')) {
    i.innerHTML = data[i.getAttribute('data-value')];
}

<script>

Php infected javascript:

.... <script>document.write(gen_simple())</script> ....

plus if in 'I was never here' mode:

....
<script>
for (var i of document.querySelectorAll('script')) i.parentNode.removeChild(i);
</script>



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Wednesday, November 18th, 2015 code javascript utils • 145w
So we always start:

var canvas = document.getElementById("canvas");
var c = canvas.getContext("2d");

and we have the basic:

c.fillRect
c.fillText
c.strokeRect
c.strokeText

and for all other shapes we use paths

I use a lot of circles so why not add:

c.fillCircle
c.strokeCircle

We can do that by adding some functions to the prototype of the c with is the CanvasRenderingContext2D:

CanvasRenderingContext2D.prototype.fillCircle = function(x, y, r) {
  this.beginPath();
  this.arc(x, y, r, 0, 2 * Math.PI);
  this.fill();
};

CanvasRenderingContext2D.prototype.strokeCircle = function(x, y, r) {
  this.beginPath();
  this.arc(x, y, r, 0, 2 * Math.PI);
  this.stroke();
};


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Monday, November 16th, 2015 code css html javascript • 136w
To have a canvas as a html page background we need:

HTML:

<body onload="load()">
  <canvas id="canvas_back"></canvas>
  ...
</body>

CSS:

#canvas_back {
  position: fixed;
  top: 0px;
  left: 0px;
  z-index: -1;
}

JavaScript:

var c, w, h;

function load() {
  var canvas = document.getElementById("canvas_back");
  c = canvas.getContext("2d");

  window.addEventListener('resize', resize, false);
  resize();
}

function resize() {
  w = canvas.width = window.innerWidth;
  h = canvas.height = window.innerHeight;
  draw();
}

function draw() {
  // use c, w and h to draw the canvas
  ...
  requestAnimationFrame(draw);
}


Demo 1


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Wednesday, November 11th, 2015 code javascript utils • 121w
To store values to a browser we can use localStorage and sessionStorage just by:

localStorage["name"] = value;

and to get the values we just:

value = localStorage["name"];

The localStorage keeps the values for ever (probably).
The sessionStorage keeps the values until the page session ends.

For each domain our browser has a pair of these objects and not for each page.

To store objects without functions we use JSON:

localStorage["name"] = JSON.stringify(object);
object = JSON.parse(localStorage["name"]);


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Monday, November 9th, 2015 code javascript utils • 75w
If we want to use JQuery ONLY for selecting elements like:

$(".item")

Why use a whole library, just:

document.querySelectorAll(".item")

or

function q(query) {
  return document.querySelectorAll(query);
}

q(".item")

Note: The only thing we gain from this is self-something.


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