js filereader

How to Implement inheritance in js (five inheritance methods in js) and five inheritance methods in jsJs inheritance has five implementation methods:1. The first method of inheritance: Object impersonatingFunction Parent (username ){This. username = username;This. hello = function (){Alert (this. username );}}Function Child (username, password ){// Use the following three lines to append the Parent attribut

This article mainly introduces node. use q. js implements api promise. promise is a standard that describes the returned results of asynchronous calls, including correct returned results and error handling, need a friend can refer to what is promise and promise solution is what problem, please experience node callback asynchronous coding method, along with the step http://wiki.commonjs.org/wiki/Promises/A to see how it is set, here I will not go into

1. Event.preventdefault (); --The default event that blocks the element.Note: A element of the click-Jump default event, Default event for form elements such as Button,radio, div element has no default event Cases: Copy Code code as follows: Copy Code code as follows: var samp = Document.getelementbytagname ("a"); Samp.addeventlistener ("click", Function (e) {e.preventdefault ()},false); Explanation: Click on the link when the normal will occur

This article mainly introduces node. in js, You Can format numbers to add thousands of characters. This article provides three implementation methods and provides the instance Code respectively. For more information, see the processing method separated by commas (,). Regular Expression mode: The Code is as follows: "15000000 ". split (""). reverse (). join (""). replace (/(\ d {3})/g, "$1 ,"). split (""). reverse (). join (""); "115000000". split ("

This article mainly introduces node. buffer in js. the usage of the copy method. This article introduces the buffer. copy method description, syntax, receive parameters, use instances, and implement Source Code. For more information, see Method description: Replace the buffer. Copy data from the source buffer and replace it with the specified location of the target buffer. Syntax: The Code is as follows: Buffer. copy (targetBuffer, [targetS

This article mainly introduces node. emitter in js. the usage of the on method is described in this article. on Method description, syntax, receive parameters, use instances and implementation source code. For more information, see Method description: Registers a listener for a specified event. Syntax: The Code is as follows: Emitter. on (event, listener)Emitter. addListener (event, listener) Receiving parameters: Event (string) event TypeThe call

This article mainly describes how to use the path. dirname method in node. js. This article describes the method description, syntax, usage examples, and source code implementation of path. dirname. For more information, see Method description: Returns the path directory. Similar to UNIX directory commands. Syntax: The Code is as follows: Path. dirname (p) Because this method belongs to the path module, You need to introduce the path module (var p

This article describes how to use the path. isAbsolute method in node. js. This article describes the method description, syntax, examples, and source code implementation of path. isAbsolute. For more information, see Method description: Checks whether the path is an absolute path. An absolute path will be resolved to the same location, whether in the working directory or not. Syntax: The Code is as follows: Path. isAbsolute (path) Because this me

This article mainly introduces Custom Event instances in node. js. A simple example. For more information, see the EventEmitter that inherits events, then you can register the event through the on; emit triggers the event and removeListener removes the event. A simple example is as follows: Var util = require ('util'); var Et = require ('events '). eventEmitter; function Ticker () {var self = this; setInterval (function () {self. emit ("tick")

example, the desktop computer we are using now, whether PC or Mac, is x86/x64, which is Little-endian.Use DataView , not only can solve the above mentioned memory alignment problem, you can also specify the read-write byte order, the specific parameters are in the document, do not carry.Using DataView the mate typed array can also be a technique for detecting the current platform byte order:functionIslittleendian () {varBUF =NewArrayBuffer (2); varView =NewDataView (BUF); View.setint16 (0, 256,

Http://bbs.blueidea.com/thread-2430778-1-1.html) I sorted out several common webpage advertisement codes. Demo address:Http://www.makewing.com/lanren/js/01/index.htmHttp://www.makewing.com/lanren/js/02/index.htmHttp://www.makewing.com/lanren/js/03/index.htmHttp://www.makewing.com/lanren/js/04/index.htmHttp://www.makewi

Now there are a lot of mature image upload plugin, because before the image upload has not been contacted, do not understand its implementation principle. Online access to the relevant information to understand that it is based on the FileReader Api.As we all know, everyone usually do compatibility is to be compatible with the lower version of the browser, image upload is the opposite. Browser-based security policy, the file tag has not been available

Step by step teach you how to build the node. js service under win7 What is node. js? Return the server-side JavaScript? In this articleArticleIf you do not want to explain it, you can search and find out that server-side JS is not a new technology, but a recent node. the popularity of JS broke out. I will explain wha

Beginning in March, received a new task, with UI development, using angular js,express JS and other technologies. So the weekend to learn new technology.The product UI structure in the group is as follows:One of the front-end, mainly using angular JS frame, in addition to cooperate with Bootstrap to provide a lot of control and jquery, backstage is mainly Express

multithreading): Default to each tab page a process, do not affect each other. Main role for page rendering, script execution, event handling, etc. Enhanced Memory: opening a Web page in a browser is equivalent to a new process (within the process has its own multithreading) two. The focus is on the browser kernel (rendering process) The point is, we can see that there are so many processes mentioned above, so what is the ultimate for a normal front-end operation? The answer is the rendering

Objectivefile reads are an essential interface for improving application experience because file operations are frequently required in programming scenarios。JS processing file read, due to security considerations, before 2000, are to "HTML5, the mainstream browser engine supports the new file API, provides a files array for "HTML5 provides a prototype filereader that can be used to get 4 main methods throug

, and the IMG element src is the user's computer local address. Iv. Realization OFNext we use FileReader's readasdataurl to get the data URI scheme to achieve the function of picture preview, and ie5.5~ 9 We will use the filter DXImageTransform.Microsoft.AlphaImageLoader to make the downgrade process.HTML fragment:ifLTE IE9]>"file"Onchange="Showpreview (this);"/>"Preview">JS Fragment:varPreview =function (EL) {varPV = document.getElementById ("Preview

1. Get to input node first2. read files with FileReader objects3. After the file is read, there will be a callback function to get the resultExample: var files = $ (' #fileImport '). Prop (' Files '); get to File list varnew FileReader (); Create a new FileReader Reader.readastext (Files[0], "UTF-8"); Read file function will come back here after reading

object is img ) The original size is 4000*3000, now need to limit the size to 400*300 size, very simple, the principle is as follows code:var canvas = document.createelement (' canvas '); var context = Canvas.getcontext (' 2d '); canvas.width = 400;canvas.height = 300;//Core JS on this context.drawimage (img,0,0,400,300);Draw a large picture directly on a small canvas. At this time the big picture will naturally become a small picture, compression is

the post-cutting base64 data, the background to write a corresponding route is good. jquery does not have to say much, page display control and AJAX submissions. Html5/filereader/canvas,filereader is used to read the file as data, we use its onLoad event, canvas, which is used as a trim move, redraws the cropped picture in real time (equivalent to real-time preview, of course I was hidden, When deb