javascript-events

问题 A couple of questions here: I was wondering what event do I use to execute some javascript on form submission (to do some validation)? Once I have done my validation, how do I then submit the form in javascript ? Cheers... 回答1: Let's say you have a form named myForm : var form = document.getElementById('myForm'); To catch submission: try { form.addEventListener("submit", someFunction, false); } catch(e) { form.attachEvent("onsubmit", someFunction); //Internet Explorer 8- } Note: If you want

问题 If I call clearTimeout for a setTimeout event that has already fired but whose callback is still on the execution queue, will the clearTimeout still prevent that event from being processed? In other words, is it still possible to clear a timeout event during the delay of the timer firing and its callback being executed? Informally speaking, my guess is that once the timeout fires, it queues up the callback and destroys itself – making a clearTimeout with that timer's id have no effect on the

问题 I want to use the 'mouse's drag' to drag a background's position around, inside a box. The css: .filmmakers #map { width : 920px; height : 500px; margin-top : 50px; margin-left : 38px; border : 1px solid rgb(0, 0, 0); cursor : move; overflow : hidden; background-image : url('WorldMap.png'); background-repeat : no-repeat; } The html: <div id = "map" src = "WorldMap.png" onmousedown = "MouseMove(this)"> </div> The javascript: function MouseMove (e) { var x = e.clientX; var y = e.clientY; e

问题 I'm sure it's a commonly asked question but didn't find a concrete answer. I kind of understand the basic concept of NodeJS and it's asynchronous/non-blocking nature of processing I/O. For argument sake, let's take a simple example of a HTTP server written in node that executes the unix command 'find /' and writes the result to the http response (therefore displaying the result of the command on the user's browser). Let's assume that this takes 3 seconds. Let's assume that there are two users

问题 I am creating a html page which contains a question ( a puzzle like situation ). The answer for the question is "Windows 7". But I want the user to get through the question only if he presses windows key followed by 7 . I want to create a JavaScript function for this. I am able to capture the individual key press by getting the ascii value of the keystroke. But when I try to do it combinedly its not working. How to go about solving this.. any ideas.. 回答1: http://jsfiddle.net/loktar/MsNPW/5/

问题 I have gone insane trying to figure out how to make this work. Code looks roughly like: function onDropDownChanged() { $("#updatePanel").load( "myUrl", { id: $("#myDropDown option:selected").val() }, onPanelLoaded ); } function onPanelLoaded() { $("#theTextInput").focus(); } $(document).ready(function() { $("#myDropDown").change(onDropDownChanged); } The first time the change handler is fired, it does the ajax update, and the text box is focused. However, on subsequent changes, it continues

问题 I have gone insane trying to figure out how to make this work. Code looks roughly like: function onDropDownChanged() { $("#updatePanel").load( "myUrl", { id: $("#myDropDown option:selected").val() }, onPanelLoaded ); } function onPanelLoaded() { $("#theTextInput").focus(); } $(document).ready(function() { $("#myDropDown").change(onDropDownChanged); } The first time the change handler is fired, it does the ajax update, and the text box is focused. However, on subsequent changes, it continues

问题 I don't have enough rep to post my own answer just yet, but here it is before I waste more peoples' time: Ok, I now understand why I don't get all of the expected ancestors: JQuery datepicker deletes the parent node (the datepicker-head) onclick. After that my event is triggered on the button of the element that already got deleted. So now I am "trapped" in the scope of the deleted element and can only traverse up to the deleted container itself. I think I can work out a solution for my event

问题 I want to add change event to a group of checkboxes, how can I access this in my event function, so that when I do the event I can access value of the checkbox. This is my current code. var checkboxes = document.getElementsByClassName('cb'); Array.from(checkboxes).forEach(function(){ this.addEventListener("change", cbChange(this), false); }); function cbChange(ele){ console.log(ele.value); } <input class="cb" type="checkbox" name="candidate" value="1"/> <input class="cb" type="checkbox" name=

问题 I have the following code : function createImage(source) { var pastedImage = new Image(); pastedImage.onload = function() { } pastedImage.src = source; } The function createImage contain the source parameter which contain the source of an image. After that I created the object pastedImage of class Image and after alerting that I am getting the html image element object like [object HTMLImageElement] . My question is how I can display image into my html page using that object. I want to