Pointer Events In 15 Minutes

swap doms
var div_cont = document.createElement('div');

var div1 = document.createElement('div');
div1.setAttribute('id', 'div1');
div1.innerHTML = 'Div One';

var div2 = document.createElement('div');
div2.setAttribute('id', 'div2');
div2.innerHTML = 'Div Two';

but aqua glare = [];
div_array[0] = div1;
div_array[1] = div2;

for (var i=0; i<div_array.length; i+=1) {
    div_cont.appendChild(div_array[i]);
}

document.body.appendChild(div_cont);

div_cont.onclick = function() {

    if (div_array[0] === div1){
        div_array[0] = div2;
        div_array[1] = div1;
    } else if (div_array[0] === div2){
        div_array[0] = div1;
        div_array[1] = div2;
    }

    for (var i=0; i<div_array.length; i+=1) {
        div_cont.appendChild(div_array[i]);
    }
}

swap doms by css only
table-header-group
table-footer-group
table-row-group

/* the functional important stuff */
.container { display:table;}
.div1 { display:table-footer-group;  }
.div2 { display:table-row-group;}
.div3 { display:table-header-group;}

<div class="container">
 <div class="div1">   <span>1</span> </div>
 <div class="div2">   <span>2</span> </div>
 <div class="div3">   <span>3</span> </div>
</div>

Using CSS
element{ display: table-footer-group; }
Using Javascript
object.style.display="table-footer-group";

body onload multiple functions
function start(){
    func1();
    func2();
    func3();
}

body onload="start()"

list all arrays in JavaScript
var house = ["red","blue","yellow"];
var car = ["fast","big","safe"];
var sofa = ["cozy","modern","elegant"];
var arrayCount = 0;
var arrayString = "";
for (var property in window) {
    if (Array.isArray(window[property])){
        arrayCount++;
        arrayString += arrayCount > 1 ? ", " + property : property;
    }
}
console.log(arrayCount + " arrays - " + arrayString);

canvas draw circle
<canvas id="myCanvas" width="300" height="150" style="border:1px solid #d3d3d3;">

var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.arc(100, 75, 50, 0, 2 * Math.PI);
ctx.stroke();

Centerarc(100,75,50,0*Math.PI,1.5*Math.PI)  // Center 100,75
Start anglearc(100,75,50,0,1.5*Math.PI)     // Start angle 0
End anglearc(100,75,50,0*Math.PI,1.5*Math.PI) // End angle 1.5*Math.PI
context.arc(x,y,r,sAngle,eAngle,counterclockwise);

create a circle with arc(): Set start angle to 0 and end angle to 2*Math.PI.
Use the stroke() or the fill() method to actually draw the arc on the canvas.

remove null value from array
Math.min(...[].concat(...dataDiff).filter(function(val) { return val !== null }))

remove max and min
  arr.filter(e => e != Math.min(...arr));
  arr.filter(e => e != Math.max(...arr));