下面给出解决办法。 例 4.1_a function check() { var form = document.getElementById("regForm"); if (form.user.value == "") { alert("用户名不能为空!"); } else { form.submit(); } } 用户 <INPUT TYPE="button" onclick="check();" id="regBut" value="提交"/> 或者用下面...
If caused by a click, the clicked element is available as the relatedTarget property of the event. hide.bs.modal This event is fired immediately when the hide instance method has been called. hidden.bs.modal This event is fired when the modal has finished being hidden from the user (will ...
Is null false in JavaScript? Null is not considered false in JavaScript, but it is considered falsy. This means that null is treated as if it’s false when viewed through boolean logic. However, this is not the same thing as saying null is false or untrue. ...
Keeps the tooltip within the bounds of this element. Example: viewport: '#viewport' or { "selector": "#viewport", "padding": 0 } If a function is given, it is called with the triggering element DOM node as its only argument. The this context is set to the tooltip instance. Data at...
(b.filter.ID=function(e){var t=e.replace(te,ne);return function(e){return e.getAttribute("id")===t}},b.find.ID=function(e,t){if("undefined"!=typeof t.getElementById&&E){var n=t.getElementById(e);return n?[n]:[]}}):(b.filter.ID=function(e){var n=e.replace(te,ne);...
It returns a boolean true if a match is found and a boolean false when no match is found. For example: // usage 1: using pure JavaScript document.getElementById('#email').hasAttribute('name'); // usage 2: using jQuery jQuery('#email')[0].hasAttribute('name'); // usage 3...
console.log(isEmptyObject(null));//output: false Advertisement 4.Object.entries() TheObject.entries()method returns an array of arrays, with each element being an array of key-value pairs of an object’s property. Let’s go through the following example to understand how it works exactly....
indexOf(4).should.equal(-1); }); }); context('when present', function() { it('should return the index where the element first appears in the array', function() { [1, 2, 3].indexOf(3).should.equal(2); }); }); }); }); ...
The most commonly used DOM method isgetElementById. It takes one parameter: a case-sensitive string with the element’s identifier. It returns anelementobject, which is referenced to the element if it exists; otherwise, it returns null. ...
exists(x) Check if x exists. This is based on a null, undefined and false check. has.spaces(str) Check if string str has any spaces. has.class(elm, class) Check if element elm has the class name class. has.extension(str, ext) Check if string str has an extension in array ext.ex...