JavaScript: Unterschied zwischen den Versionen
Zur Navigation springen
Zur Suche springen
Zeile 26: | Zeile 26: | ||
</script> | </script> | ||
</pre> | </pre> | ||
= Methoden = | |||
<pre>var hypotenuse = function(a,b) { return Math.sqrt(a*a+b*b); } | |||
console.log(hypotenuse(1, 44)); | |||
</pre> | |||
= Strikte Gleichheit = | |||
* a == b: Referenzvergleich | |||
* a === b: Inhaltsvergleich | |||
= Typen = | = Typen = | ||
== String == | == String == | ||
<pre>text += "."; | <pre>text += "."; | ||
"xyz".substr(1, 2) === "y"; | |||
"abc".indexOf("bc") === 1; | |||
"abcb".replace("b", "x") === "axcb"; | |||
</pre> | </pre> | ||
Zeile 41: | Zeile 53: | ||
</pre> | </pre> | ||
== Arrays == | |||
<pre>a=[1, 2, "wow"]; | |||
a0=a.shift(); a === [2, "wow"]; | |||
a.push(99); a === [2, "wow", 99]; | |||
a.concat([2, 3]) === [2, "wow", 99, 2, 3]; | |||
[1, 3, 5, 9].slice(0,2) === [1, 3] && [1, 3, 5, 9].slice(2,3) === [3]; | |||
</pre> | |||
= Klassen = | = Klassen = | ||
<pre>'use strict'; | <pre>'use strict'; |
Version vom 23. Mai 2018, 10:14 Uhr
DOM-Elemente finden
var list = document.getElementsByTagName("UL")[0]; var elem = document.getElementById("xyz");
Einbindung in HTML
<button onclick="myFunction()">Click me</button>
<p onclick="myFunction()">Click me to change my text color.</p> <script> function myFunction() { document.getElementById("demo").style.color = "red"; }
<button onclick="myFunction()">Copy Text</button> <script> function myFunction() { document.getElementById("text2").value = document.getElementById("text2").value; document.getElementById("textarea2").innerHTML = document.getElementById("textarea2").innerHTML; var field = document.getElementById("field1"); field.style.visibility = field.style.visibility == "hidden" ? "visible" : "hidden"; } </script>
Methoden
var hypotenuse = function(a,b) { return Math.sqrt(a*a+b*b); } console.log(hypotenuse(1, 44));
Strikte Gleichheit
- a == b: Referenzvergleich
- a === b: Inhaltsvergleich
Typen
String
text += "."; "xyz".substr(1, 2) === "y"; "abc".indexOf("bc") === 1; "abcb".replace("b", "x") === "axcb";
Numbers
- Nur Gleitpunktzahlen werden benutzt.
- Daher haben Ganzzahlen max. 53 Bit
- x=Math.min(1,2,3); r=Math.floor(x); w=Math.sqrt(x);
Dictionary
var x = { "zahl" : 33, "pair" : { "x" : true } };
Arrays
a=[1, 2, "wow"]; a0=a.shift(); a === [2, "wow"]; a.push(99); a === [2, "wow", 99]; a.concat([2, 3]) === [2, "wow", 99, 2, 3]; [1, 3, 5, 9].slice(0,2) === [1, 3] && [1, 3, 5, 9].slice(2,3) === [3];
Klassen
'use strict'; class Polygon { constructor(height, width) { this.name = 'Polygon'; this.height = height; this.width = width; } sayName() { ChromeSamples.log('Hi, I am a ', this.name + '.'); } sayHistory() { ChromeSamples.log('"Polygon" is derived from the Greek polus (many) ' + 'and gonia (angle).'); } static className() { return "Polygon"; } } const p = new Polygon(300, 400); p.sayName();