JavaScript Math functions examples
AD MOB
List of usefull JavaSript functions and constans
var 1_radian_to_degree = 180 / Math.PI; // 57,295779513082320876798154814105 degree
var 1_degree_to_radian = Math.PI / 180; // 0,01745329251994329576923690768489 radian
var 360_degree = 2 * Math.PI * 1_radian_to_degree;
parseInt("10.33") // returns 10 string to integer
parseFloat("10.33") // returns 10.33 string to float
// change sign
var a = -1;
a = a * -1; // +1
// random sign
a *= Math.floor(Math.random()*2) == 1 ? 1 : -1;
var who_is = 58;
var type = (typeof who_is); // number
Math.E // natural logarithms, e, approximately 2.718281828459045
Math.LN10 // natural logarithm of 10, approximately 2.302585092994046
Math.LN2 // natural logarithm of 2, approximately 0.6931471805599453
Math.PI // approximately 3.141592653589793
Math.SQRT1_2 // square root of 1/2 which is approximately 0.7071067811865476
Math.SQRT2 // square root of 2, approximately 1.4142135623730951
Math.pow(4, 2) = 16 // 4 x 4 ... base 4 to the exponent 2 power
Math.abs(-5) absolute value of a number // return 5
Math.tan(degrees * Math.PI / 180) // get tangent from degrees
Math.tan(degree * Math.PI / 180)*adjacent = opposite
opposite / Math.tan(degree * Math.PI / 180) = adjacent
Math.acos(adjacent / hypotenuse) // angle of a right-angle triangle in radians
Math.atan(opposite / adjacent) // angle of a right-angle triangle in radians
var adjacent = Math.cos(radian) * hypotenuse; // leng of adjacent side
// find the point on a circle if you know the circle´s radius
var x = Math.cos(pointAngleInRadiansFromCentreOfCircle) * radius;
var y = Math.sin(pointAngleInRadiansFromCentreOfCircle) * radius;
Math.cbrt(64) // cube root of a number 4 (4 x 4 x 4)
Math.exp(xNumber) // returns e<sup>xNumber</sup> ... e == Math.E
Math.ceil() // always rounds a number up to the next largest integer
Math.ceil(1.001) // 2
Math.floor() // returns largest integer less than or equal to a given number
Math.floor(5.85) = 5
Math.floor(-5.15) = -6
const arrayA = [2, 3, 1];
Math.min(...arrayA) = 1;
Math.max(1, 3, 2) = 3;
Math.random() // returns 0.000.... - 0.99999999999
Math.random() * 3 // returns 0.000 - 2.99999999999
Math.round() // returns value of a number rounded to the nearest integer.
Math.round(0.9) // 1
Math.round(5.5) // 6
Math.round(5.05) // 5
Math.floor(Math.random() * 3) // returns 0, 1, 2
Date: 14.06.2020 - 08:3877LW NO topic_id
AD
Další témata ....(Topics)
IPV6 má jiný formát znaků a pokud se hlásíme na stránku pomocí IP tak navíc může být pokaždé jiná
i když dříve jsme měli pokaždé stejnou. Takže jak na to v php.
Získám IP adresu pomocí funkce:
Získanou adresu definuji jako konstantu, ALE jen tu část začátku, které se shoduje z IP například s předešlého dne
a ta bude vždy stejná:
Tu část pak porovnávám při kontrole zda se jedná o mou adresu:
i když dříve jsme měli pokaždé stejnou. Takže jak na to v php.
Získám IP adresu pomocí funkce:
function getip(){
if (getenv("HTTP_CLIENT_IP")) $ip = getenv("HTTP_CLIENT_IP");
else if(getenv("HTTP_X_FORWARDED_FOR")) $ip = getenv("HTTP_X_FORWARDED_FOR");
else if(getenv("REMOTE_ADDR")) $ip = getenv("REMOTE_ADDR");
else $ip = UNKNOWN;
return $ip;
}
Získanou adresu definuji jako konstantu, ALE jen tu část začátku, které se shoduje z IP například s předešlého dne
a ta bude vždy stejná:
define("MY_IPV6","2b00:1027:904d:9e6z");
Tu část pak porovnávám při kontrole zda se jedná o mou adresu:
$ip = getip();
if( strpos($ip, MY_IPV6) !== false ){
// kdyz je moje IP provedu prihlaseni
}
Foreach fore each in javascript loop cycle example source code
Example code foreach for JavaScript.
var arr = new Array(1,2,3,4,5,6);// numbers or string put into array
for (var key in arr) {
window.alert("My array"
+ key
+ " = "
+ arr[key]);
}
// next example
arr.forEach(function(elem){
console.log(elem);
});
// next example
for (var i = 0; i < arr.length; i++) {
alert (arr[i]);
}
// next example for GECKO MOZILLA FIREFOX
var soucet = 0;
var obj = {var1: 5, var2: 13, var3: 8};
for each (var item in obj) {
soucet += item;
}
alert(soucet); // vysledek "26", coz je soucet 5+13+8
Each in jQuery get all document inputs type text and set value 0 if checkbox checked
function fc(th){
if( th.checked ){
$("input:text").each(
function() {
this.value = 0;
this.disabled = true;
}
);
}else{
$("input:text").each(
function() {
this.disabled = false;
}
);
}
<input type="checkbox" id="idCheck" onchange="fc(this);"> Checkbox
<input type="text" size="1" id="id1" value="0" />
<input type="text" size="1" id="id2" value="0" />
How to sort array in javascript.
sort diacritical diakritika
function sortCZ(a, b) {
var token = {'á': 'a', 'č': 'c', 'ď': 'd', 'é': 'e', 'ě': 'e', 'í': 'i', 'ň': 'n', 'ř': 'r', 'š': 's', 'ť': 't', 'ú': 'u', 'ů': 'u', 'ý': 'y', 'ž': 'z'};
var code_a = (token[a]) ? token[a].charCodeAt(0) + 0.5 : a.charCodeAt(0);
var code_b = (token[b]) ? token[b].charCodeAt(0) + 0.5 : b.charCodeAt(0);
// example s=115 š will 115.5 in array immediately after s OK :)
if(token[a]){
some = token[a].charCodeAt(0) + 0.5; // 115.5
some = token[a].charCodeAt(0); // 115
}
return code_a - code_b;
}
var ar = new Array("x","č","a","c","h","z","a","ř","e","ž","ě","ň","í","d","š");
ar.sort(sortCZ);
For all browsers e.g. old IE 11 ....
<script>
var mbThreadOneRunning = false;
var mbThreadOneEnded = false;
var mbThreadTwoRunning = false;
var mbThreadTwoEnded = false;
// you can create more than one Thread
// setTimeout() used for running more Threads at once
var timeout_1 = setTimeout("ThreadOne()", 5000); // 5000 == 5 second
var timeout_2 = setTimeout("ThreadTwo()", 3000); //
function ThreadOne() {
mbThreadOneRunning = true;
alert("1. ThreadOne working!");
// working code here .............
mbThreadOneEnded = true;
clearTimeout(timeout_1);
}
function ThreadTwo() {
mbThreadTwoRunning = true;
alert("2. ThreadTwo working!");
// working code here .............
mbThreadTwoEnded = true;
clearTimeout(timeout_2);
}
var mInterval = setInterval("checkThread()", 1000); // 1000 ms == 1 second, you can put smaller value
function checkThread() {
if (mbThreadOneEnded == true) {
alert("1. checkThread() ThreadOne finish work! " + mbThreadOneEnded);
}
else if (mbThreadTwoEnded == true) {
alert("2. checkThread() ThreadTwo finish work! " + mbThreadTwoEnded);
}
if (mbThreadOneEnded && mbThreadTwoEnded) {
clearInterval(mInterval); // just to be sure
mbThreadOneEnded = false;
mbThreadTwoEnded = false;
alert("ThreadOne and ThreadTwo ended ");
}
}
</script>
Tohle jsou některé metody objektu document
clear
createDocument
createDocumentFragment
createElement
createEvent
createEventObject
createRange
createTextNode
getElementById
/* nejpouzivanejsi metoda objektu document, ktera
ziska handle elementu dle jeho id*/
getElementByTagName
var e = document.getElementById('list');
e= e.getElementsByTagName('span');
i=0;
while(i < e.length){
e[i].style.color = "green";
}
write
document.write("some text");
Editace: 20.6.2020 - 08:32
Počet článků v kategorii: 77
Url:javascript-math-functions-constans-examples
AD