关于JavaScript或jQuery跨域读取服务端api报错：

“jquery-3.2.1.min.js:4  Access to XMLHttpRequest at 'https://******.xyz/api/WhatAppLink**.asmx/JaColak' from origin 'https://j.investluck.xyz' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.send @ jquery-3.2.1.min.js:4”。如下图：

此处报错已经提示：“access-control-allow-origin”，这里需要在服务端应用端配置access-control-allow-origin，加入Access-Control-Allow-Origin "*"。此跨域权限不限于.NET、jsp、PHP都有这个跨域设置，这里我们服务端采用.NET，所以在webconfig中配置相应设置,即开启了跨域权限，如下：

WebConfig 代码  复制
<?xml version="1.0" encoding="utf-8"?>
<configuration>
	<system.webServer>
		<httpProtocol>
			<customHeaders>
				<add name="Access-Control-Allow-Origin" value="*"/>
				<add name="Access-Control-Allow-Methods" value="GET,PUT,POST,DELETE,OPTIONS"/>
				<add name="Access-Control-Allow-Headers" value="Content-Type"/>
			</customHeaders>
		</httpProtocol>
	</system.webServer>
</configuration>