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Here is an example of an error handling function in a Web Worker JavaScript file that logs errors to the console.ExampleWith error handling code, above example would become like the following: Big for loop var worker = new Worker('bigLoop.js'); worker.onmessage = function (event) { alert("Completed " + event.data + "iterations" ); }; worker.onerror = function (event) { console.log(event.message, event); }; function sayHello(){ alert("Hello sir...." ); }
JavaScript was designed to run in a single-threaded environment, meaning multiple scripts cannot run at the same time. Consider a situation where you need to handle UI events, query and process large amounts of API data, and manipulate the DOM.JavaScript will hang your browser in situation where CPU utilization is high. Let us take a simple example where Javascript goes through a big loop: Big for loop function bigLoop(){ for (var i = 0; i
To resize the image before submitting the form, you need to use the drawImage() method.Scale the original image and draws the scaled version on the canvas at [0,0]context.drawImage( img, 0,0,img.width,img.height, 0,0,myWidth,UseHeight );Above, we saw the following:Here,var myWidth = Math.floor( img.width * Scale ); var myHeight = Math.floor( img.height * Scale );And,var x = Math.floor( ( world.width - myWidth) / 2 ); var y = Math.floor( ( world.height - myHeight) / 2 );
The DataTransfer object holds data about the drag and drop operation. This data can be retrieved and set in terms of various attributes associated with the DataTransfer object.The following are the attributes:Sr.No.DataTransfer attributes and their description1dataTransfer.dropEffect [ = value ]Returns the kind of operation that is currently selected.This attribute can be set, to change the selected operation.The possible values are none, copy, link, and move.2dataTransfer.effectAllowed [ = value ]Returns the kinds of operations that are to be allowed.This attribute can be set, to change the allowed operations.The possible values are none, copy, copyLink, copyMove, link, linkMove, move, all and uninitialized.3dataTransfer.typesReturns a DOMStringList ... Read More
To accept a drop, the drop target has to listen to at least three events. The dragenter event, which is used to determine whether the drop target is to accept the drop. If the drop is to be accepted, then this event has to be canceled. The dragover event, which is used to determine what feedback is to be shown to the user. If the event is canceled, then the feedback (typically the cursor) is updated based on the dropEffect attribute's value. Finally, the drop event, which allows the actual drop to be performed.
The event listener methods for all the drag and drop events accept Event object that has a readonly attribute called dataTransfer. The event.dataTransfer returns DataTransfer object associated with the event as follows:function EnterHandler(event) { DataTransfer dt = event.dataTransfer; … }You can try to run the following code to implement DataTransfer object: #boxA, #boxB { float:left;padding:10px;margin:10px; -moz-user-select:none; } #boxA { background-color: #6633FF; width:75px; height:75px; } #boxB { background-color: #FF6699; width:150px; height:150px; } ... Read More
To make an image scale on mouse over, use Vanilla JavaScript library.On mouse move, set it like the following:function move(e) { var pos = getMousePos(myCanvas, e); context.drawImage(img, -pos.x, -pos.y, img.width, img.height); }For canvas://add event listener we need myCanvas.addEventListener('mouseout', display, false); myCanvas.addEventListener('mousemove', move, false);function display() { context.drawImage(img, 0, 0, img.width>>1, img.height>>1); }
Maybe, you are using += with innerHTML. Try the following:var myNum = [1,2,3]; var myStr; myStr = ""; for( var a in myNum) myStr += "" + a + ""; myStr += ""; id("numberList").innerHTML = myStr;
To pass values, let us say our is the following, with page new.html,StructureThe JS will be:$( document ).on( "pageinit", "#new", function( event ) { var myParam = $(this).data("url").split("?")[1]; myParam = parameters.replace("structure=",""); alert(myParam); });
No, you will not be able to prevent the prompt. It is a security feature because not every user would want to share its location.As stated by W3C:A conforming implementation of this specification must provide a mechanism that protects the user's privacy and this mechanism should ensure that no location information is made available through this API without the user's express permission.