javascript 如何解决：被 CORS 策略阻止：请求的资源上不存在“Access-Control-Allow-Origin”标头
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How to solve: Blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource
提问by diwakar g
I am trying to call javascript using visualforce (VF) page. On clicking preview in VF page, method is executed. But, when I tried to see the response in Google chrome getting "blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource" error. Below is the sample code for VF.
我正在尝试使用 Visualforce (VF) 页面调用 javascript。在 VF 页面点击预览，方法被执行。但是，当我尝试在 Google chrome 中看到响应时出现“被 CORS 策略阻止：请求的资源上不存在‘Access-Control-Allow-Origin’标头”错误。下面是 VF 的示例代码。
<apex:page controller="calljavascript_cls" >
<script>
function func()
{
var request = new XMLHttpRequest();
request.open('GET', 'https://copado.herokuapp.com/json/v1/webhook/metadata/AAAA?api_key=BBBB');
request.onreadystatechange = function () {
if (this.readyState === 4) {
console.log('Status:', this.status);
console.log('Headers:', this.getAllResponseHeaders());
console.log('Body:', this.responseText);
}
};
request.send();
}
</script>
<apex:outputText value="{!callfunc}" escape="false"></apex:outputText>
</apex:page>
Apex controller class:
Apex控制器类：
public class calljavascript_cls
{
public string callfunc{get;set;}
public calljavascript_cls()
{
callfunc='<script> func(); </script>';
}
}
I tried the solutions given in below link. Not working.
我尝试了以下链接中给出的解决方案。不工作。
Don't know how to proceed. Please help me.
不知道如何继续。请帮我。
回答by vengleab so
You need to set header "Access-Control-Allow-Headers" on request, and your server must also allow set header "Access-Control-Allow-Headers", sth call CORS
您需要根据请求设置标头“Access-Control-Allow-Headers”，并且您的服务器还必须允许设置标头“Access-Control-Allow-Headers”，调用 CORS
request.setRequestHeader('Access-Control-Allow-Headers', '*');
