javascript xhr.upload.onprogress 不起作用
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时间：2020-10-26 20:52:53 来源:igfitidea点击:
xhr.upload.onprogress doesn't work
提问by user1534664
Everything in the following code will work, except it will never fire the xhr.upload.onprogress event.
以下代码中的所有内容都将起作用，除了它永远不会触发 xhr.upload.onprogress 事件。
$(function(){
var xhr;
$("#submit").click(function(){
var formData = new FormData();
formData.append("myFile", document.getElementById("myFileField").files[0]);
xhr = new XMLHttpRequest();
xhr.open("POST", "./test.php", true);
xhr.send(formData);
xhr.onreadystatechange = function(){
if(xhr.readyState === 4 && xhr.status === 200){
console.log(xhr.responseText);
}
}
xhr.upload.onprogress = function(e) {
// it will never come inside here
}
});
});
回答by VoidMain
You should create the listeners before opening the connection, like this:
您应该在打开连接之前创建侦听器，如下所示：
$(function(){
var xhr;
$("#submit").click(function(){
var formData = new FormData();
formData.append("myFile", document.getElementById("myFileField").files[0]);
xhr = new XMLHttpRequest();
xhr.onreadystatechange = function(){
if(xhr.readyState === 4 && xhr.status === 200){
console.log(xhr.responseText);
}
}
xhr.upload.onprogress = function(e) {
// it will never come inside here
}
xhr.open("POST", "./test.php", true);
xhr.send(formData);
});
});
Hope that helps.
希望有帮助。
