function lookup() { firstName = /\w+/i(); if (!firstName) window.alert (RegExp.input + "非法输入"); else { count=0; for (i=0;i 输入你的姓然后按回车键。 <FORM><INPUT TYPE:"TEXT" NAME="FirstName" onChange="lookup(this);"></
jQuery.isEmptyObject({});// true 2 jQuery.isEmptyObject({"foo":"1"});// false Conclusion In this article, we discussed a number of different ways to check if an object is empty or not in JavaScript. Check out some of our other tutorials about JavaScript programming!
// then run the following block.if (!argument) { return 'The argument is empty'} else { return 'The argument is not empty'} // Let's convert the previous block to a positive check const argument = null if (argument) { return 'The argument is present'} else { return 'The argument...
如果我们要基于不同的类型调用不同的方法,可以使用多个 else if 语句或 switch,但有没有比这更好的简化技巧呢? // Longhandif(type==='test1'){test1();}elseif(type==='test2'){test2();}elseif(type==='test3'){test3();}elseif(type==='test4'){test4();}else{thrownewError('Invalid va...
Last week, I shared how tocheck if an input is empty with CSS. Today, let’s talk about the same thing, but with JavaScript. It’s much simpler. Here’s what we’re building: Events to validate the input If you want to validate the input when a user types into the field, you ca...
When the string is not null or undefined, and you intend to check for an empty one, you can use the length property of the string prototype, as follows:Javascript empty string 1 2 3 4 let emptyStr = ""; if (!emptyStr && emptyStr.length == 0) { console.log("String is empty")...
prototype, 'init', { enumerable: false, value: function () { 'use strict'; if (new.target) { throw new TypeError('init is not a constructor'); } var fun = function () { console.log(this.name); } fun.call(this); } }) 解析:此题的关键在于是否清楚 ES6 的 class 和普通构造...
if(x.trim() == "") throw "is empty"; if(isNaN(x)) throw "is not a number"; x = Number(x); if(x > 10) throw "is too high"; if(x < 5) throw "is too low"; } catch(err) { message.innerHTML = "Error: " + err + "."; } finally { document.getElementById("demo...
Pre-release Check App Release SDK Privacy and Security Statement Fields Variable Data Types Extension Template Fields iOS Version Change History Getting Started Preparations Configuring App Information in AppGallery Connect Integrating the SDK Operations on the Server Permissions Enablin...
Install npm install javascript-time-ago --save If you're not using a bundler then use astandalone version from a CDN. Use importTimeAgofrom'javascript-time-ago'// English.importenfrom'javascript-time-ago/locale/en'TimeAgo.addDefaultLocale(en)// Create formatter (English).consttimeAgo=newTimeAg...