typescript - What does "@" symbol mean in "import { Component } from '@angular/core';" statement?

hoogw2017-12-20

@scope_name/package_name

This is NPM feature, scoped name, anything between @ and slash / will be your scope name.

npm scope document

create-react-app 卡住报错 - No matching version found for browserslist@^4.19.1

Ivan Sukach 2021-12-22

常识下面的命令清除缓存：

npm cache clean --force

语法解释：接口前的下划线"_"的用处

zzzz 2012-11-02

type ValueConverter interface {
    // ConvertValue converts a value to a driver Value.
    ConvertValue(v interface{}) (Value, error)
}

var Bool boolType

type boolType struct{}

var _ ValueConverter = boolType{} // line 58

func (boolType) String() string { return "Bool" }

func (boolType) ConvertValue(src interface{}) (Value, error) {....}

如何disable(灰化)chrome插件的pageAction?

TestWell 2022-10-02

Chrome documents this behavior in their docs: https://developer.chrome.com/docs/extensions/reference/action/#emulating-pageactions-with-declarativecontent. The following describes how to achieve it in manifest v3.

// background.js

chrome.runtime.onInstalled.addListener(() => {
  // disable the action by default
  chrome.action.disable();

  // remove existing rules so only ours are applied
  chrome.declarativeContent.onPageChanged.removeRules(undefined, () => {
    // add a custom rule
    chrome.declarativeContent.onPageChanged.addRules([
      {
        // define the rule's conditions
        conditions: [
          new chrome.declarativeContent.PageStateMatcher({
            pageUrl: { hostSuffix: "reddit.com" },
          }),
        ],
        // show the action when conditions are met
        actions: [new chrome.declarativeContent.ShowAction()],
      },
    ]);
  });
});

This will require the declarativeContent permission in manifest.json

{
  ...
  "permissions": ["declarativeContent"]
  ...
}

CORS: 设置Access-Control-Allow-Origin HEADER例子

gen_Eric 2013-09-05

不允许设置多个origin，需要服务器自己判断设置origin，或者只能设置*。

Access-Control-Allow-Origin: *

Access-Control-Allow-Origin: http://localhost:8080

Access-Control-Allow-Origin: https://developer.mozilla.org/

k8s如何列出service的pods？

Vidyasagar Machupalli 2020-02-14

1. Find the selector by running the below command

kubectl get services -o=wide

Output:

NAME                  TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)   AGE   SELECTOR
hello-world-service   ClusterIP   172.21.xxx.xx   <none>        80/TCP    13m   run=nginx

2. Pass the selector to the command below

kubectl get pods --selector=run=nginx -o=name

Docker处于 Created 状态的原因

kstromeiraos 2017-05-02

Docker status Created means that the container has been created from the image, but it has never been started.

This state can be achieved in this two ways.

1. Docker container has been created using docker create command (this is done to speed up container creation).

2. Docker container has been created using docker run but it hasn't been able to start successfully.

For further information check docker create reference: https://docs.docker.com/engine/reference/commandline/create/

如何查看Docker Image的dockerfile？

themozel 2020-08-24

You can also regenerate the dockerfile from an image or use the docker history <image name> command to see what is inside. check this: Link to answer

So if you have a docker image that was built by a dockerfile, you can recover this information (All except from the original FROM command, which is important, I’ll grant that. But you can often guess it, especially by entering the container and asking “What os are you?”). However, the maker of the image could have manual steps that you’d never know about anyways, plus they COULD just export an image, and re-import it and there would be no intermediate images at that point.

mongodb - createdCollectionAutomatically的意思

Gerald Mücke 2016-05-31

详细查看从下面链接: https://docs.mongodb.com/manual/reference/command/createIndexes/#output

createdCollectionAutomatically 的意思是：是否创建了新的collection，如果是false，表示没有创建，如果是true，表示创建了新的colletion

例子：运行 db.myCollection.createIndex({"address":1}),如果myCollection不存在的话，结果如下所示：

{
    "createdCollectionAutomatically" : true,
    "numIndexesBefore" : 1, // 命令运行前索引的数量
    "numIndexesAfter" : 2, // 命令允许后的索引数量
    "ok" : 1
}

jquery删除除第一个元素以外的子元素

Hulk 2013-09-18

jquery删除部分子元素的例子

Nigel 2013-09-18

page action 和 browser action 的区别是什么？

Makyen 2017-06-23

Browser Action buttons are intended to be used when your extension can be used most of the time, or on most pages. They also allow you to provide some immediately visible status information to the user by having a badge containing a couple/few characters over the icon and changing the color of the background used for that badge.

Page Action buttons are intended for use when your extension is often/usually not available for use. For instance, if it's only usable on a few domains or URLs.

javascript 例子：检查列表中是否包含某个元素？

David 2013年7月29日

Array的indexOf() 函数返回元素的位置，如果不存在则返回-1

 var array1 = [1,3,4,5,6,8,9,10];
 var a = array1.indexOf(46); //a = -1; if not found

contenteditable 元素相关事件

function setChangeListener (div, listener) {
    div.addEventListener("blur", listener);
    div.addEventListener("keyup", listener);
    div.addEventListener("paste", listener);
    div.addEventListener("copy", listener);
    div.addEventListener("cut", listener);
    div.addEventListener("delete", listener);
    div.addEventListener("mouseup", listener);
}

var div = document.querySelector("someDiv");
setChangeListener(div, function(event){
    console.log(event);
});

CSS如何令文字垂直居中？

This is the simplest way to do it if you need multiple lines. Wrap you span'd text in another span and specify its height with line-height. The trick to multiple lines is resetting the inner span's line-height.

<span class="textvalignmiddle"><span>YOUR TEXT HERE</span></span>

.textvalignmiddle {
    line-height: /*set height*/;
}

.textvalignmiddle > span {
    display: inline-block;
    vertical-align: middle;
    line-height: 1em; /*set line height back to normal*/
}

jQuery onClick 中如果禁止click事件传递?

Rushil Sablania 2013-08-06

举例:

<script>
   $(".DAY").click(
      function(event) {
         event.preventDefault();
         alert('Picked: '+ $(this).attr('id').slice(4));
      }
   );
</script>