React-fetch post content-type changes when viewed in a violin

Question

I have a selection where the types of requests seem to be changing, which will ruin my post. I provide the main form (only one field). Here is a sample.

      handleSubmit(event, data) {
    //alert('A name was submitted: ' + this.state.value);
    event.preventDefault();
    console.log("SUBMIT STATE::", this.state.value);
    return (
        fetch("//localhost:5000/api/values/dui/", {
            method: "post",
            mode: 'no-cors',
            headers: {
                'Access-Control-Allow-Origin': '*',
                'Content-Type': 'application/json',
                'Accept': 'application/json',                  
            },
            body: JSON.stringify({
                name: this.state.value,
            })
        }).then(response => {
            if (response.status >= 400) {
                this.setState({
                    value: 'no greeting - status > 400'
                });
                throw new Error('no greeting - throw');
            }
            return response.text()
        }).then(data => {
            var myData = JSON.parse(data);
            this.setState({
                greeting: myData.name,
                path: myData.link
            });
        }).catch(() => {
            this.setState({
                value: 'no greeting - cb catch'
            })
        })
    );


}

But when I look at this, the content-type fiddler now has "content-type: text / plain; charset = UTF-8". Here is the raw violinist:

POST http://localhost:5000/api/values/dui/ HTTP/1.1
Host: localhost:5000
Connection: keep-alive
Content-Length: 16
accept: application/json
Origin: http://evil.com/
User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36

content-type: text / plain; charset = UTF-8 Referer: http: // localhost: 3000 /  Accept-Encoding: gzip, deflate, br Accept-Language: en-US, en; q = 0.8

{"name":"molly"}

In the DOM Inspector, I just see:

POST http: // localhost: 5000 / api / values ​​/ dui / 415 (Unsupported media type)

, "accept" - , "content-type". , . .

Answer 1

mode: 'no-cors', , CORS, . :

/ (/) Headers (), :

5. , guard "request-no-cors", name/value CORS-safelisted request-header, .

return " ".

, text/plain;charset=UTF-8 , , , :

:

↪ USVString

• Content-Type text/plain;charset=UTF-8.

Answer 2

, , "no-cors" "cors". , , , - , , , , , : "cors", , , . , . - , .

.