alert

08React中事件的写法总结

浪尽此生 提交于 2020-01-14 19:40:16
1:事件与原生事件类型 react中式on+首字母大写的事件名 例如onClick 如图 只需要on以后常用的事件都会提示出来 2:在Content.js中新建一系列的按钮来对事件进行学习 2.1 普通的函数绑定 <button onClick={function(){alert('6666')}}>按钮1</button> 2.2 箭头函数的绑定 <button onClick={()=>{ alert("7777"); }}>按钮2</button> 2.3 箭头函数带参数 <button onClick={(e)=>{ e.target.style.color="red"; }}>按钮3</button> 2.4 页面部分 <button onClick={ this.show }>按钮4</button> 在render的上面定义一个函数 细节看alert中的提示 constructor(props){ super(props); this.state={ num:10 } //this.show9 = this.show9.bind(this); } show(){ alert("按钮4被点击 但是里面this会脱离上下文关系"); alert(this.state.num);//报错 this是undefined } 2.5 利用箭头函数 对this指向进行加强

JS基础篇1:HTML嵌入JS的三种方式

孤人 提交于 2020-01-14 14:49:45
文章目录 第一种方式:window.alert 第二种方式:脚本块的方式 第三种方式:js脚本文件,src=路径 JavaScript的简介: 1.要实现的功能: 用户点击以下按钮,弹出消息框,JS是一种实现浏览器动态、互动的。 2.JS是一门事件驱动型的编程语言 ,依靠事件去驱动,然后执行对应的程序。 在JS中有很多事件,其中有一个事件叫做:鼠标单击,单词:click.并且任何事件都会对应一个事件句柄叫做:onclick。 【注意: 事件和事件句柄的区别 是:事件句柄是在事件单词前添加一个on。】而事件句柄是以HTML标签的属性存在。 3.οnclick=“js代码”,执行原理是什么? 页面打开的时候,js代码并不会执行,只是把这段js代码注册到按钮的click事件上了。 等这个按钮发生click事件之后,注册在onclick后面的js代码会被浏览器自动调用。 4.怎么使用JS代码弹出消息框? 在js中有个内置的对象叫做window,全部小写,可以直接拿来使用,window代表的是浏览器 window对象有一个函数叫做:alert,用法是: window.alert(“消息”); 这样就可以弹窗了。 5.JS中的字符串可以使用双引号,也可以使用单引号; JS中的一条语句结束之后可以使用分号";",也可以不用。 外面单引号,里面双引号,反之。 第一种方式:window.alert

How to automatically close an alert after a certain time React Native

孤者浪人 提交于 2020-01-14 11:55:27
问题 I would like to automatically close an alert after a couple of seconds without having the user do it themselves. If possible I would like to do this using Alert (not AlertIOS), but if only AlertIOS has it then I guess I have no other choice. Thank you very much! 回答1: I suggest you use Modal component <Modal animationType={"slide"} transparent={false} visible={this.state.modalVisible}></Modal> So you can call setTimeout() in your function to update the state variable modalVisible to show /

How to automatically close an alert after a certain time React Native

生来就可爱ヽ(ⅴ<●) 提交于 2020-01-14 11:53:58
问题 I would like to automatically close an alert after a couple of seconds without having the user do it themselves. If possible I would like to do this using Alert (not AlertIOS), but if only AlertIOS has it then I guess I have no other choice. Thank you very much! 回答1: I suggest you use Modal component <Modal animationType={"slide"} transparent={false} visible={this.state.modalVisible}></Modal> So you can call setTimeout() in your function to update the state variable modalVisible to show /

How to automatically close an alert after a certain time React Native

最后都变了- 提交于 2020-01-14 11:53:45
问题 I would like to automatically close an alert after a couple of seconds without having the user do it themselves. If possible I would like to do this using Alert (not AlertIOS), but if only AlertIOS has it then I guess I have no other choice. Thank you very much! 回答1: I suggest you use Modal component <Modal animationType={"slide"} transparent={false} visible={this.state.modalVisible}></Modal> So you can call setTimeout() in your function to update the state variable modalVisible to show /

Display alert box upon form submission

拜拜、爱过 提交于 2020-01-14 10:41:37
问题 So I have these two pages: pageOne.php and pageTwo.php .The form is in pageOne.php : <form method="post" action="pageTwo.php"> .... </form> and doing all the data collection-validation-insertion and sending out mails in pageTwo.php (the reason i'm doing everything in two separate pages is to avoid the data re-submission upon page refresh...this was the easiest way for me to handle the issue). So far everything is working perfectly. Now, I want to display a success/failure message using alert

Display alert box upon form submission

笑着哭i 提交于 2020-01-14 10:41:13
问题 So I have these two pages: pageOne.php and pageTwo.php .The form is in pageOne.php : <form method="post" action="pageTwo.php"> .... </form> and doing all the data collection-validation-insertion and sending out mails in pageTwo.php (the reason i'm doing everything in two separate pages is to avoid the data re-submission upon page refresh...this was the easiest way for me to handle the issue). So far everything is working perfectly. Now, I want to display a success/failure message using alert

javascript alert() function not working in UWP app

人盡茶涼 提交于 2020-01-14 10:26:31
问题 I used some little basic javascript code and used it to make a simple UWP app, the alert function in the code works when i run the file in the browser, but it doesnt work when i try it in UWP app. below is the code <!DOCTYPE html> <html> <head> <meta charset="utf-8" /> <title>App6</title> <!-- WinJS references --> <link href="WinJS/css/ui-dark.css" rel="stylesheet" /> <script src="WinJS/js/base.js"></script> <script src="WinJS/js/ui.js"></script> <!-- App6 references --> <link href="/css

javascript中的this

狂风中的少年 提交于 2020-01-13 20:57:33
this是Javascript语言的一个关键字。 它代表函数运行时,自动生成的一个内部对象,只能在函数内部使用。 函数在不同的执行环境中this的值也跟着不同。 分一下四种 方法调用模式。 当函数作为对象的方法调用时,this指向该对象 var num1=0; var obj={}; obj.num1=1; obj.func=function(){ return this.num1; } alert(obj.func());//1    普通的函数调用模式 当函数直接调用时,this指向全局对象window。 var num1=0; var func=function(){ return this.num1; } alert(func())//0    当函数内部的函数用普通调用方式调用时,this仍指向全局对象window。 var num1=0 var obj={}; obj.num1=1; obj.func1=function(){ var num1=2; var that=this; var func2=function(){ alert(this.num1);//0 alert(that.num1);//1 alert(num1);//2 } func2(); } obj.func1();    构造器调用模式,即使用new关键词 当使用new方式调用函数时

js判断文件大小利用img 的 dynsrc,兼容IE10 及以上

守給你的承諾、 提交于 2020-01-12 08:48:15
原文链接 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> < html xmlns = "http://www.w3.org/1999/xhtml" > < head > < meta name = "DEscription" contect = "my code demo" /> < meta name = "Author" contect = "Michael@jb51.net" /> < meta http-equiv = "Content-Type" content = "text/html; charset=utf-8" /> < meta http-equiv = "X-UA-Compatible" content = "IE=emulateIE8" > < title > js check file size @ jb51.net </ title > </ head > < body > < img id = "tempimg" dynsrc = "" src = "" style = "display:none" /> < input type = "file" name = "file" id