Tag Archives: javascript

On and off of timer in JS

setInterval()
When a function
is called for a specified period of time:

setInterval(function,time,lang)

function: function to be called or code string to be executed
time: required parameters, every how long to call the function, in milliseconds
lang: optional parameters, running JScript | VBScript | JavaScript
clearInterval()
Means to stop the setInterval timer call function

function getTime() {
        console.log(123);
        if (true) {
            clearInterval(db)
        }
    }

let db = setInterval(getTime, 1000)

setTimeout()
Call a function after a certain time
syntax:

setTimeout(function,time,lang)

Function:
function: required, to be called
time: required, number of milliseconds to wait before executing code
lang: optional, script language: JScript | VBScript | JavaScript

A Chrome extension to protect the privacy of personal favorites

As a programmer, I often have to share my desktop with others due to the demands of my work.
But I don’t want people to see my browser favorites when I share the desktop, as follows:

I could, of course, hide the entire favorites bar using the Ctrl+Shift+B shortcut, but that would make it inconvenient for me to use it myself:

Later I found a nice Chrome Bookmarks extension: Neater Bookmarks:

After clicking on the extension icon in the upper right corner of the screen, my favorites will be displayed in a tree structure:

For example, the Angular folder is expanded this time. Next time you click on the Icon of the Favorites, the rendered tree structure will still be expanded Angular folder:

The extension id: ofgjggbjanlhbgaemjbkiegeebmccifi
Extended link: https://chrome.google.com/webstore/detail/ofgjggbjanlhbgaemjbkiegeebmccifi
More of Jerry’s original articles, all in: “wang zixi” :

AngularJS: Error reports on $injector:modulerr

The most common problem Angular JS has is that an application has failed to launch with an error of $Injector: Modulerr
The error was caused by a failure to load the corresponding Module, but it was difficult to find the Module that needed to be modified.
A simple trick is not to use Angular.min.js, but to use Angular.js. At this point, AngularJS gives detailed error information, which is very helpful in troubleshooting errors.
This is the error I see when I use Angular.js, so I simply remove the $translateProvider issue.
angular.js:68 Uncaught Error: [$injector:modulerr] Failed to instantiate module acTodoApp due to:
Error: [$injector:unpr] Unknown provider: $translateProvider
http://errors.angularjs.org/1.5.5/$injector/unpr?24 translateprovider p0 = %

at http://localhost:1337/node_modules/angular/angular.js:68:12 at http://localhost:1337/node_modules/angular/angular.js:4458:19
It’s for the record.
Alva Chien,
2016.5.2

Attempted import error: ‘injectglobal’ is not exported from ‘styled components’

I. Emergence of Problems:

    , in the previous project development, the error occurred when applying male-components , applying injectGlobal to define style variables, and injectGlobal 'is not exported from' application-components '.

Ii. Analysis and Solution of problems:
The reason for

    problem is that The injectGlobal API was removed and removed by createGlobalStyle in styled-components v4. API is removed and replaced by malt-components v4. Replaced with createGlobalStyle the new API appears as a style component and is introduced as a label based on the style component idea. InjectGlobal cannot be applied directly as the original injectGlobal. We define a global style variable that will be inserted into the document as a component. Solution:

The first step is to define the global style with createGlobalStyle and wrap the global style in it. Wrap the CSS style with the back-quotation string, as shown below:

import { createGlobalStyle } from 'styled-components'

export const Globalstyle = createGlobalStyle`　
body{
　　margin: 0;
　　padding: 0
　}`

The second step is to import the style in the project main file. The code is as follows:

import { Globalstyle } from './style'

The third step is introduced as a label in the form of a style component, as shown below:


class App extends Component {
  render () {
    return (
      <Fragment>
        <GlobalStyled/>
      </Fragment>
    )
  }
}

mac Error: EACCES: permission denied, mkdir ‘./cache’

My system is MAC. I am typing the following command:

sudo npm install -g aglio

The following problems arise:

npm WARN deprecated [email protected]: CoffeeScript on NPM has moved to "coffeescript" (no hyphen)
npm WARN deprecated [email protected]: Jade has been renamed to pug, please install the latest version of pug instead of jade
npm WARN deprecated [email protected]: Please update to at least constantinople 3.1.1
npm WARN deprecated [email protected]: Deprecated, use jstransformer
npm WARN deprecated [email protected]: This version is no longer maintained. Please upgrade to the latest version.
npm WARN deprecated [email protected]: This version is no longer maintained. Please upgrade to the latest version.
npm WARN deprecated [email protected]: This version is no longer maintained. Please upgrade to the latest version.
npm WARN deprecated [email protected]: Please update to minimatch 3.0.2 or higher to avoid a RegExp DoS issue
/usr/local/bin/aglio -> /usr/local/lib/node_modules/aglio/bin/aglio.js

> [email protected] install /usr/local/lib/node_modules/aglio/node_modules/fsevents
> node install

node-pre-gyp WARN Using request for node-pre-gyp https download
node-pre-gyp WARN Pre-built binaries not installable for [email protected] and [email protected] (node-v57 ABI, unknown) (falling back to source compile with node-gyp)
node-pre-gyp WARN Hit error EACCES: permission denied, mkdir '/usr/local/lib/node_modules/aglio/node_modules/fsevents/lib'
gyp WARN EACCES user "root" does not have permission to access the dev dir "/Users/eric/.node-gyp/8.12.0"
gyp WARN EACCES attempting to reinstall using temporary dev dir "/usr/local/lib/node_modules/aglio/node_modules/fsevents/.node-gyp"
gyp WARN install got an error, rolling back install
gyp WARN install got an error, rolling back install
gyp ERR! configure error
gyp ERR! stack Error: EACCES: permission denied, mkdir '/usr/local/lib/node_modules/aglio/node_modules/fsevents/.node-gyp'
gyp ERR! System Darwin 18.0.0
gyp ERR! command "/usr/local/bin/node" "/usr/local/lib/node_modules/npm/node_modules/node-gyp/bin/node-gyp.js" "configure" "--fallback-to-build" "--module=/usr/local/lib/node_modules/aglio/node_modules/fsevents/lib/binding/Release/node-v57-darwin-x64/fse.node" "--module_name=fse" "--module_path=/usr/local/lib/node_modules/aglio/node_modules/fsevents/lib/binding/Release/node-v57-darwin-x64" "--napi_version=3" "--node_abi_napi=napi"
gyp ERR! cwd /usr/local/lib/node_modules/aglio/node_modules/fsevents
gyp ERR! node -v v8.12.0
gyp ERR! node-gyp -v v3.8.0
gyp ERR! not ok
node-pre-gyp ERR! build error
node-pre-gyp ERR! stack Error: Failed to execute '/usr/local/bin/node /usr/local/lib/node_modules/npm/node_modules/node-gyp/bin/node-gyp.js configure --fallback-to-build --module=/usr/local/lib/node_modules/aglio/node_modules/fsevents/lib/binding/Release/node-v57-darwin-x64/fse.node --module_name=fse --module_path=/usr/local/lib/node_modules/aglio/node_modules/fsevents/lib/binding/Release/node-v57-darwin-x64 --napi_version=3 --node_abi_napi=napi' (1)
node-pre-gyp ERR! stack     at ChildProcess.<anonymous> (/usr/local/lib/node_modules/aglio/node_modules/fsevents/node_modules/node-pre-gyp/lib/util/compile.js:83:29)
node-pre-gyp ERR! stack     at emitTwo (events.js:126:13)
node-pre-gyp ERR! stack     at ChildProcess.emit (events.js:214:7)
node-pre-gyp ERR! stack     at maybeClose (internal/child_process.js:915:16)
node-pre-gyp ERR! stack     at Process.ChildProcess._handle.onexit (internal/child_process.js:209:5)
node-pre-gyp ERR! System Darwin 18.0.0
node-pre-gyp ERR! command "/usr/local/bin/node" "/usr/local/lib/node_modules/aglio/node_modules/fsevents/node_modules/node-pre-gyp/bin/node-pre-gyp" "install" "--fallback-to-build"
node-pre-gyp ERR! cwd /usr/local/lib/node_modules/aglio/node_modules/fsevents
node-pre-gyp ERR! node -v v8.12.0
node-pre-gyp ERR! node-pre-gyp -v v0.10.3
node-pre-gyp ERR! not ok
Failed to execute '/usr/local/bin/node /usr/local/lib/node_modules/npm/node_modules/node-gyp/bin/node-gyp.js configure --fallback-to-build --module=/usr/local/lib/node_modules/aglio/node_modules/fsevents/lib/binding/Release/node-v57-darwin-x64/fse.node --module_name=fse --module_path=/usr/local/lib/node_modules/aglio/node_modules/fsevents/lib/binding/Release/node-v57-darwin-x64 --napi_version=3 --node_abi_napi=napi' (1)

> [email protected] install /usr/local/lib/node_modules/aglio/node_modules/protagonist
> node-gyp rebuild

gyp WARN EACCES user "root" does not have permission to access the dev dir "/Users/eric/.node-gyp/8.12.0"
gyp WARN EACCES attempting to reinstall using temporary dev dir "/usr/local/lib/node_modules/aglio/node_modules/protagonist/.node-gyp"
gyp WARN install got an error, rolling back install
gyp WARN install got an error, rolling back install
gyp ERR! configure error
gyp ERR! stack Error: EACCES: permission denied, mkdir '/usr/local/lib/node_modules/aglio/node_modules/protagonist/.node-gyp'
gyp ERR! System Darwin 18.0.0
gyp ERR! command "/usr/local/bin/node" "/usr/local/lib/node_modules/npm/node_modules/node-gyp/bin/node-gyp.js" "rebuild"
gyp ERR! cwd /usr/local/lib/node_modules/aglio/node_modules/protagonist
gyp ERR! node -v v8.12.0
gyp ERR! node-gyp -v v3.8.0
gyp ERR! not ok

> [email protected] postinstall /usr/local/lib/node_modules/aglio/node_modules/aglio-theme-olio
> node scripts/setup-cache.js

fs.js:885
  return binding.mkdir(pathModule._makeLong(path),
                 ^

Error: EACCES: permission denied, mkdir './cache'
    at Object.fs.mkdirSync (fs.js:885:18)
    at Object.<anonymous> (/usr/local/lib/node_modules/aglio/node_modules/aglio-theme-olio/scripts/setup-cache.js:14:6)
    at Module._compile (module.js:653:30)
    at Object.Module._extensions..js (module.js:664:10)
    at Module.load (module.js:566:32)
    at tryModuleLoad (module.js:506:12)
    at Function.Module._load (module.js:498:3)
    at Function.Module.runMain (module.js:694:10)
    at startup (bootstrap_node.js:204:16)
    at bootstrap_node.js:625:3
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: [email protected] (node_modules/aglio/node_modules/fsevents):
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: [email protected] install: `node install`
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: Exit status 1
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: [email protected] (node_modules/aglio/node_modules/protagonist):
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: [email protected] install: `node-gyp rebuild`
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: Exit status 1

npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! [email protected] postinstall: `node scripts/setup-cache.js`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the [email protected] postinstall script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /Users/eric/.npm/_logs/2019-02-14T00_47_21_128Z-debug.log

According to the research, the correct approach should be:

 sudo npm install -g aglio --unsafe-perm=true --allow-root

And then it’s normal.
reference
[1].Error: EACCES: permission denied, mkdir ‘/root/.nvm/versions/node/……. https://www.jianshu.com/p/6c67a456654b

Uncaught typeerror: cannot set property ‘of null error resolution

This is a common bug in front-end page development, and it’s not the first time I’ve encountered it. But since I don’t often write front-end code, I have to remember the reason and the solution every time I encounter it again, so write it down in case I encounter it again.
Bug back
The project USES an Ext component, requiring an image to be displayed on the page and the image address passed in as a parameter from the previous page. My simple idea is to create a new Pannel and write an HTML code block inside it. The code block looks like this

"<img id='qrImage' src='com/system/empty.bmp' width='100%' height='100%'>"

The initial address of the image is a temporary image. When we get the image address we need to display, we will use the DOM of the operation page to set it to the new address. The address length is set as follows:

document.getElementById("qrImage").src = filePath;

It looks like there is no problem, but when the page loads, an error is reported. The error is in the above statement, and the error message is:

Uncaught TypeError: Cannot set property 'src' of null

solution
Not often write the front end suddenly scared, my first reaction turned out to be that there was something wrong with the method to get ID, such as misspelling of letter case and so on. After all, she was a careless girl. However, the harsh reality is that the W3C told me there was nothing wrong with the approach.
since not get property method no problem (actually it can’t be a method name write wrong, or the browser will report is not a function), it must be written the dom itself has a problem. The most intuitive way is of course debug, bug is also relatively simple, follow up to find the problem.
why
“Document.getelementbyid (” qrImage”) “here, the code does not get an element whose Id is” qrImage “, so it is null. Null does not have a set attribute, so the browser will throw this error:

Uncaught TypeError: Cannot set property 'src' of null

Then the rendering of the page will stop and the page will report an error.
The solution
The solution is to make sure that the element qrImage is rendered and available to the browser before the properties are set, so that no errors are reported. My project actually USES the Ext component and USES ExtBuilder to simplify development (in case my writing doesn’t work in other situations) by replacing the code with:

var infoPanel = Ext.getCmp("saveQR");
infoPanel.html = "<img id='qrImage' src=\"" + url+ "\" width='100%' height='100%'>";

The problem can be solved.
tips
For those who are not using Ext or Ext development components, you can use window.load or AfterRender methods to make sure that the page is loaded before you do anything with it.

The garbage plug-in mixed in chrome causes an error in the front-end JS operation: only one instance of Babel Polyfill is allowed

NPM recently compiled a Vue project and ran it under Chrome, and got off to a bad start:
What r.d. fine is not a function
What is only one instance of babel-polyfill is allowed
I’m surprised that it works fine in QQ browser speed mode, but it doesn’t work well in chrome.
This is the bottom left side of the junk plug-ins, I don’t know when mixed into the Chrome browser. Chrome’s plugin is also written by JS, and it gets mixed up in the same programming domain as its own, causing interference. This thing loads all the other NPM components in the mess.

Vue element El input search to achieve anti shake @ input event requests frequently

Do not use the @input event of EL-input, use this event, use buffering does not work. The actual code is as follows:

<template>
 <el-input suffix-icon="el-icon-search" v-model="page.searchCode" clearable></el-input>
</template>
<script>
	data() {
	    return {
	      timer: '',
	      page:{
	      	searchCode:''
	      }
	    }
	  },
	  watch: {
	    'page.searchCode': {
	      deep: true,
	      handler(newVal, oldVal) {
	        // if (newVal.trim().length !== 0) {
	         //this.getList is a method called after a delay of 500ms.
	        this.debounce(this.getList, 500) 
	        // }
	      }
	    }
	  },
	  methods: {
	    debounce(fn, wait) {
	      if (this.timer !== null) {
	        clearTimeout(this.timer)
	      }
	      this.timer = setTimeout(fn, wait)
	    }
	  },
	  getList(){}//The request can be written in here.
	}
</script>

Nuxt cannot find the static resource in static

Nuxt cannot find the static resource inside static reason
The old VUE project was migrated because the project needed it. Then follow the tutorial to create the SRC folder in Nuxt, and that’s why. Because the initial directory for srcDir is set. So I can’t find the folder outside of SRC.
Solution: Don’t put old project folders in SRC. Follow the folder location where the project was created to

PHP big file upload problem (500m or above)

An overview,
 
A breakpoint is simply a download, which means to continue downloading a file from where it has already been downloaded. Breakpoints were not supported in previous versions of the HTTP protocol, and HTTP/1.1 has been since. The Range and content-Range headers are usually used for breakpoints. HTTP protocol itself does not support breakpoint upload, you need to implement their own.
 
Second, the Range
 
Used in the request header to specify the position of the first byte and the position of the last byte, in general format:
 
Range: For client-to-server requests, you can change a field to specify the size and unit of a download file. Byte offset starts at 0. Typical format:
Ranges: (unit=first byte Pos)-[last byte Pos]
Ranges: Bytes =4000- Download from the beginning of byte 4000 to the end of file
Ranges: Bytes =0~N to download contents in the 0-n byte range
Ranges: Bytes = M-n to download contents in the M-n byte range
Ranges: Bytes = -n to download the last N-byte content

 
1. The following points should be noted:
(1) The data interval is a closed interval with a starting value of 0, so a request like “Range: Bytes =0-1” is actually two bytes at the beginning of the request.
(2) “Range: Bytes =-200”, which does not represent the 201 bytes at the beginning of the request file, but the 200 bytes at the end of the request file.
(3) If the last Byte POS is less than the first Byte POS, then the Range request is invalid. The server needs to ignore the Range request, then respond with a 200, and send the entire file to the client.
(4) If the last Byte POS was greater than or equal to the file length, then the Range request was considered unsatisfiable and the server needed to respond to a 416, Requested Range not Satisfiable.
 
2. Example explanation:
Bytes =0-499 bytes
Bytes =500-999 bytes
Bytes =-500 bytes
Bytes =500- = range after 500 bytes
First and last bytes: Bytes =0-0,-1
Also specify a range: Bytes =500-600,601-999
 
Third, the Content – Range
 
Used in the response header to specify the insertion location of a portion of the entire entity, which also indicates the length of the entire entity. Before the server returns a partial response to the client, it must describe the extent of the response coverage and the entire entity length. General format:
 
Content-range: Bytes (Unit first Byte pos) – [Last Byte pos]/[Entity Legth]
 
4. Header examples
 
Request to download the entire file:
 
GET/test. Rar HTTP/1.1
Connection: close
Host: 116.1.219.219
Range: Bytes =0-801 // Bytes =0- Or don’t use this header
 
General normal response
 
HTTP/1.1 200 OK
The Content – Length: 801
The content-type: application/octet stream
Content-range: Bytes 0-800/801 //801: Total file size
 
The simplest breakpoint continuation implementation is as follows:
1. The client has downloaded a 1024K file, of which 512K has been downloaded
2. The network is interrupted, and the client requests the continuation of transmission. Therefore, it is necessary to declare the fragment to be continued this time in the HTTP header:
Range:bytes=512000-
This header tells the server to transfer the file from the 512K location of the file
3. The server receives the breakpoint to continue the transmission request, starting from the 512K position of the file, and adds in the HTTP header:
Content-Range:bytes 512000-/1024000
And the server should return an HTTP status code of 206 instead of 200.
However, in a real scenario, the content of the file corresponding to the URL has changed at the server side when the terminal initiates the continuation request, and the data of the continuation is definitely wrong. How to solve this problem?Obviously at this point we need a way to identify the uniqueness of the file. There is also a definition in RFC2616, such as last-modified to indicate the Last modification time of a file, so that you can determine whether any changes have been made during the continuation of the file. Also defined in RFC2616 is an ETag header that can be used to place a unique identifier for a file, such as the MD5 value of the file.
When a terminal initiates a continuation request, it should declare the IF-match or IF-modified-since fields in the HTTP header to help the server identify file changes.
In addition, there is also an IF-range header defined in RFC2616. If the terminal USES iF-range in continuation. The content in the IF-range can be the first ETag header received or the Last modification in the Last-ModFIED. When the server receives the continuation request, it verifies through the contents in the IF-range. If the verification is consistent, it returns the continuation reply of 206; If not, it returns 200. The content of the reply is all the data of the new file.

the relevant reference links: http://blog.ncmem.com/wordpress/2019/08/09/http%e6%96%ad%e7%82%b9%e7%bb%ad%e4%bc%a0/
welcome into the group to discuss: 374992201