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Learn how to separate JavaScript code into external files and include them in HTML for reusability. Explore error handling, events, and actions in HTML documents.
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JavaScript in extern files JavaScript canbeseparated from the html file (eg myscripts.js ) and thenbeincluded in the html file wherethey is used – the source canthenalsobereused in different html files.It works as the source wereplaced in the html documentdirectly. <script type="text/javascript” src=”myscripts.js”> </script>
Error handling try { // code witch might fail } catch(err) { // error handling eg. alert("Error description: " + err.description); }
Events - musseposition • Mouse-events used for fun • <script type="text/javascript"> • document.onmousemove=moveWin; // mowe when mouse is moved to the window • function moveWin() • { • var x = event.clientX; • var y = event.clientY; • x = x+10; • y = y+10; • document.all.knap1.style.position = "absolute"; • document.all.knap1.style.left = ""+x; • document.all.knap1.style.top = ""+y; • window.status=x+" : "+y; • } • </script> • <html> • <body> • <input id="knap1" type=button value=”Catch me" style="position: absolute" /> • </body> • </html> • more here: http://www.javascriptkit.com/jsref/event.shtml
Action when a field is left whth mouse click or keyboard • A small script that change the text of an input field to uppercase when you ar leaving the field. • <html> • <head> • <script type="text/javascript"> • function upperCase() • { • var x=document.all["fname"].value; • document.all["fname"].value = x.toUpperCase(); • } • </script> • </head> • <body>Enter your name: • <input type="text" id="fname" onmouseout="upperCase();" onblur="upperCase();"> • </body> • </html>
Action when you load and unload the html document • A drill page - something that's often used online to force you to stay on a page • <script type="text/javascript"> • this.id = "drillewindue"; • var nyWindow = null; • function luk () // public metode på winduet • { • alert("lukker også andet window"); • if (nyWindow!=null)nyWindow.close(); • } • function createNewDoc() • { • var windowURL = ""; • var windowID = ""; • var windowProperty = 'left=20,top=20,width=500,height=500,toolbar=0,resizable=0'; • nyWindow = this.open(windowURL,windowID,windowProperty); • nyWindow.document.write('<htlm><body onunload="lukny();">Window der ikke er til at lukke</body></html>'); • nyWindow.document.close(); • nyWindow.lukny = function() // public metode på winduet • { • alert("du må ikke lukke dette window"); • createNewDoc (); • } • } • </script> • <html> • <body onunload="luk()" onload="createNewDoc()"> • Drille window der åbner window der ikke kan "lukkes" • </body> • </html>
Replacing html / text items • html / text content can be replaced with properties eg. on body • document.body.innerHTML =”<br> New Content <br>”; • document.body.innerText =”New Content”; • is also good to use in conjunction with the div and span objects, which, like forms, can contain several elements.
Object collection in document • all - collection of all objects in the document • forms • applets • images • frames