javascript-events

问题 jquery on() function allow the DOM event to trigger on an element that may be inserted in the future. How can this be implemented using plain javascript especially a mouseenter event on elements with a certain class without jquery and using modern document.querySelector 回答1: Found the answer here https://developer.mozilla.org/en-US/docs/Web/Events/mouseenter For anyone interested in implementing code is below: <ul id="test"> <li> <ul class="enter-sensitive"> <li>item 1-1</li> <li>item 1-2</li

问题 There are many contentcontrols in a document and I need to find out a way that the cursor is in which content control so that I will select that control and do the operation accordingly. I think by implementing onEnter and onExit events for contentcontrols , I can achieve it. But I don't know how to declare and invoke those eventhandlers in JavaScript api. Any help is really appreciated. 回答1: You would need to use a combination of APIs to implement that functionality with the current API set:

问题 sometimes the users bind the events on $('body') and sometimes on $(document) $(document).on('click', someAction); $('body').on('click', someAction); Is there some reason to prefer one to another? 回答1: For me, there is mainly one reason to bind the events on $(document) and not to $('body') : no need to wait domReady (document is available before everything else) 回答2: Short answer most likely is, no, not really. The reason someone is doing it should always be that he requires to catch an

问题 sometimes the users bind the events on $('body') and sometimes on $(document) $(document).on('click', someAction); $('body').on('click', someAction); Is there some reason to prefer one to another? 回答1: For me, there is mainly one reason to bind the events on $(document) and not to $('body') : no need to wait domReady (document is available before everything else) 回答2: Short answer most likely is, no, not really. The reason someone is doing it should always be that he requires to catch an

问题 sometimes the users bind the events on $('body') and sometimes on $(document) $(document).on('click', someAction); $('body').on('click', someAction); Is there some reason to prefer one to another? 回答1: For me, there is mainly one reason to bind the events on $(document) and not to $('body') : no need to wait domReady (document is available before everything else) 回答2: Short answer most likely is, no, not really. The reason someone is doing it should always be that he requires to catch an

问题 sometimes the users bind the events on $('body') and sometimes on $(document) $(document).on('click', someAction); $('body').on('click', someAction); Is there some reason to prefer one to another? 回答1: For me, there is mainly one reason to bind the events on $(document) and not to $('body') : no need to wait domReady (document is available before everything else) 回答2: Short answer most likely is, no, not really. The reason someone is doing it should always be that he requires to catch an

问题 sometimes the users bind the events on $('body') and sometimes on $(document) $(document).on('click', someAction); $('body').on('click', someAction); Is there some reason to prefer one to another? 回答1: For me, there is mainly one reason to bind the events on $(document) and not to $('body') : no need to wait domReady (document is available before everything else) 回答2: Short answer most likely is, no, not really. The reason someone is doing it should always be that he requires to catch an

问题 I have a string that has comma separated values. How can I count how many elements in the string separated by comma. e.g following string has 4 elements string = "1,2,3,4"; 回答1: myString.split(',').length 回答2: var mystring = "1,2,3,4"; var elements = mystring.split(','); return elements.length; 回答3: First split it, and then count the items in the array. Like this: "1,2,3,4".split(/,/).length; 回答4: All of the answers suggesting something equivalent to myString.split(',').length could lead to

问题 I created some javascript code that submits the form out the tag. Here is the code: <script type="text/javascript"> var myForm = document.forms['myForm']; var formSubmit = document.getElementById('formSubmit'); formSubmit.onclick = function(){ myForm.submit(); } </script> <form name="myForm" action="http://msn.com" method="post"> </form> <div id="formSubmit"><button>Click me</button></div> When i try this code on http://jsfiddle.net/HrCxz/ it works fine. But When I add this code in an HTML

问题 I'm making a Web application that tests typing speeds. It gives the user some text to type, and an input box to type into. If the user types a wrong key, I'm using preventDefault on the produced key event to prevent the wrong character from being entered into the input box (I instead show the user an error message). The problem is, preventDefault doesn't prevent backspaces from being entered. Ideally, since wrong keys presses will never be entered into the text box, it doesn't make sense to