javascript接收sse打印结果。比如 目前 openai api 的 stream 返回。 标准的请求sse是 EventSource，但是这个无法像正常post一样，携带数据或者header。若你的接口需要进行鉴权，需要携带header或者body数据，像post请求一样，那么这个EventSource就没法用了。
查了一下，目前并没有直接的支持方案，一些fetch库，比如axios，也是无法支持的。
这里有一种方法，可以实现这种效果，给大家分享一下：
代码语言：javascript复制
var SSE = function (url, options) {
if (!(this instanceof SSE)) {
return new SSE(url, options);
}
this.INITIALIZING = -1;
this.CONNECTING = 0;
this.OPEN = 1;
this.CLOSED = 2;
this.url = url;
options = options || {};
this.headers = options.headers || {};
this.payload = options.payload !== undefined ? options.payload : '';
this.method = options.method || (this.payload && 'POST') || 'GET';
this.withCredentials = !!options.withCredentials;
this.FIELD_SEPARATOR = ':';
this.listeners = {};
this.xhr = null;
this.readyState = this.INITIALIZING;
this.progress = 0;
this.chunk = '';
this.addEventListener = function (type, listener) {
if (this.listeners[type] === undefined) {
this.listeners[type] = [];
}
if (this.listeners[type].indexOf(listener) === -1) {
this.listeners[type].push(listener);
}
};
this.removeEventListener = function (type, listener) {
if (this.listeners[type] === undefined) {
return;
}
var filtered = [];
this.listeners[type].forEach(function (element) {
if (element !== listener) {
filtered.push(element);
}
});
if (filtered.length === 0) {
delete this.listeners[type];
} else {
this.listeners[type] = filtered;
}
};
this.dispatchEvent = function (e) {
if (!e) {
return true;
}
e.source = this;
var onHandler = 'on' e.type;
if (this.hasOwnProperty(onHandler)) {
this[onHandler].call(this, e);
if (e.defaultPrevented) {
return false;
}
}
if (this.listeners[e.type]) {
return this.listeners[e.type].every(function (callback) {
callback(e);
return !e.defaultPrevented;
});
}
return true;
};
this._setReadyState = function (state) {
var event = new CustomEvent('readystatechange');
event.readyState = state;
this.readyState = state;
this.dispatchEvent(event);
};
this._onStreamFailure = function (e) {
var event = new CustomEvent('error');
event.data = e.currentTarget.response;
this.dispatchEvent(event);
this.close();
};
this._onStreamAbort = function (e) {
this.dispatchEvent(new CustomEvent('abort'));
this.close();
};
this._onStreamProgress = function (e) {
if (!this.xhr) {
return;
}
if (this.xhr.status !== 200) {
this._onStreamFailure(e);
return;
}
if (this.readyState == this.CONNECTING) {
this.dispatchEvent(new CustomEvent('open'));
this._setReadyState(this.OPEN);
}
var data = this.xhr.responseText.substring(this.progress);
this.progress = data.length;
data.split(/(rn|r|n){2}/g).forEach(
function (part) {
if (part.trim().length === 0) {
this.dispatchEvent(this._parseEventChunk(this.chunk.trim()));
this.chunk = '';
} else {
this.chunk = part;
}
}.bind(this),
);
};
this._onStreamLoaded = function (e) {
this._onStreamProgress(e);
// Parse the last chunk.
this.dispatchEvent(this._parseEventChunk(this.chunk));
this.chunk = '';
};
/**
* Parse a received SSE event chunk into a constructed event object.
*/
this._parseEventChunk = function (chunk) {
if (!chunk || chunk.length === 0) {
return null;
}
var e = { id: null, retry: null, data: '', event: 'message' };
chunk.split(/n|rn|r/).forEach(
function (line) {
line = line.trimRight();
var index = line.indexOf(this.FIELD_SEPARATOR);
if (index <= 0) {
// Line was either empty, or started with a separator and is a comment.
// Either way, ignore.
return;
}
var field = line.substring(0, index);
if (!(field in e)) {
return;
}
var value = line.substring(index 1).trimLeft();
if (field === 'data') {
e[field] = value;
} else {
e[field] = value;
}
}.bind(this),
);
var event = new CustomEvent(e.event);
event.data = e.data;
event.id = e.id;
return event;
};
this._checkStreamClosed = function () {
if (!this.xhr) {
return;
}
if (this.xhr.readyState === XMLHttpRequest.DONE) {
this._setReadyState(this.CLOSED);
}
};
this.stream = function () {
this._setReadyState(this.CONNECTING);
this.xhr = new XMLHttpRequest();
this.xhr.addEventListener('progress', this._onStreamProgress.bind(this));
this.xhr.addEventListener('load', this._onStreamLoaded.bind(this));
this.xhr.addEventListener('readystatechange', this._checkStreamClosed.bind(this));
this.xhr.addEventListener('error', this._onStreamFailure.bind(this));
this.xhr.addEventListener('abort', this._onStreamAbort.bind(this));
this.xhr.open(this.method, this.url);
for (var header in this.headers) {
this.xhr.setRequestHeader(header, this.headers[header]);
}
this.xhr.withCredentials = this.withCredentials;
this.xhr.send(this.payload);
};
this.close = function () {
if (this.readyState === this.CLOSED) {
return;
}
this.xhr.abort();
this.xhr = null;
this._setReadyState(this.CLOSED);
};
};
可以像这样使用：
代码语言：javascript复制 const url = 'http://localhost:8000/xxx/xxxx?a=0';
var source = new SSE(url, {
method: 'POST',
// withCredentials: true,
headers: {
'Content-Type': 'application/json',
'Cache-Control': 'no-cache',
'self-header1': 'xxxx',
'self-header2': 'xxxx',
},
payload: JSON.stringify({ // POST body
a: 'a',
b: 'b',
}),
});
source.onmessage = function (data) {
console.log('111111 onmessage', data); // data: 后面的信息
};
source.onerror = function (err) {
console.log('111111 onerror', err); // data: 后面的信息
};
source.stream();
