报错内容Uncaught DOMException: Failed to execute 'add' on 'DOMTokenList': The token provided must not be empty.解决方案传入className不能为空字符串，在add之前先判断一下即可...
闲来无事学习一下indexedDB，看前提示，我这不是学习文档，我只是把我学习的成果代码跟大家分享一下，因为我自己看文档的代码偶尔也会困惑，边写边理解，我这个代码只是给刚接触indexedDB的人一点提示。
一、学习文档
1、学习前端知识首选：MDN--indexedDB文档https://developer.mozilla.org/zh-CN/docs/Web/API/IndexedDB_API/Using_IndexedDB
2、阮一峰老师的分享文档：http://www.ruanyifeng.c
删除项目下 package-lock.json 文件
跟着升级步骤更新angular https://update.angular.io/?v=8.0-9.0
更新8最新版本： ng update @angular/core@8 @angular/cli@8
更新到9：ng update @angular/cli@9 @angular/core@9
把ng build的错误都改正
跟着步骤更新NG-ZOR
在使用vue的时候，我们因为改变了页面的
DOM
结构，可能会遇见这样的告警信息，并且页面会被卡主，需要刷新才可以解决；但是，在实际项目中，这样的情况肯定是不允许出现的。错误告警如下：
"NotFoundError:
Failed
to
execute
‘insertBefore’ on ‘Node’。
关于 v-if 和 v-show 两个指令的区别，传送门： v-if 和 v-show 的区别
js
报错
Uncaught
DOM
Exception
:
Failed
to
execute
‘getImageData’ on ‘CanvasRenderingContext2D’: The canvas has been tainted by cross-origin data.
在用
IDE
A时，调用getImageData()报跨域的错误，原因是图片存储在本地时，是默认没有域名的，用getImageData方法时，浏览器会判定为跨域而
报错
。
搜索了很多方法尝试解决，包括：
设置时间戳
var img
源码 就这么一小段，一开始是没有添加主键{autoIncrement:true}
但是添加后还是
报错
，怀疑是浏览器缓存的问题，就把浏览器中 创建的数据库给删除了，更改版本号，重新创建
Uncaught InvalidCharacterError:
Failed
to
execute
'setAttribute' on 'Element': '"' is not a valid at
在echarts使用属性visualMap对折线图进行区间的变色设置，结果写完直接
报错
：
Uncaught
DOM
Exception
:
Failed
to
execute
'
add
ColorStop' on 'CanvasGradient': The value
pro
v
ide
d ('undefined') could not be parsed as a color.
这个
报错
很有迷惑性，让我以为是哪的color设置不正确，结果搞了一下午，查出来是数据格式不正确的问题导致的。
pieces中区间的的数据
JavaScript
is a high-level, interpreted
pro
gramming language that is w
ide
ly used for front-end web development, server-s
ide
scripting, and browser scripting. It is an object-oriented language that is primarily used to create dynamic, interactive, and responsive web pages and applications.
JavaScript
is an essential technology for building modern web applications and is supported by all major browsers, including Google Chrome, Mozilla Firefox, and Internet Explorer.
Some of the key features of
JavaScript
include:
- Event-driven
pro
gramming:
JavaScript
is an event-driven language, meaning that the code is
execute
d in response to user events, such as clicking a button, scrolling the page, or hovering over an element.
- Dynamic typing: Unlike other
pro
gramming languages that have strict type checking,
JavaScript
is a dynamically typed language, meaning that the type of a variable can change during runtime.
- Asynchronous
pro
gramming:
JavaScript
is well-suited for asynchronous
pro
gramming, making it
ide
al for handling tasks that do not block the main thread of the browser, such as making API calls,
pro
cessing data, or updating the user interface.
- Function-based
pro
gramming:
JavaScript
is a functional
pro
gramming language, meaning that functions are first-
class
citizens in the language and can be used as values and passed as arguments to other functions.
Overall,
JavaScript
is a versatile and w
ide
ly-used language that is essential for modern web development.
