How upload photo using fetch?

Question

I try to upload photo from my PC using fetch, but code below doesn't work. Url is right. What is the problem?

 static async sendPostFormDataRequest(url) {
    let formData = new FormData();
    formData.append("nameField", "C://sample.jpeg");
    fetch(url, {
        method: "POST",           
        body: formData
    })
}