129 lines
3.6 KiB
JavaScript
129 lines
3.6 KiB
JavaScript
function getContentType(headers) {
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if(!headers) {
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return;
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}
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for(let key in headers) {
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if(key.toLowerCase() === "content-type") {
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return headers[key];
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}
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}
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}
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// Inspired by `resp-modifier` https://github.com/shakyShane/resp-modifier/blob/4a000203c9db630bcfc3b6bb8ea2abc090ae0139/index.js
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function wrapResponse(resp, transformHtml) {
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resp._wrappedOriginalWrite = resp.write;
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resp._wrappedOriginalWriteHead = resp.writeHead;
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resp._wrappedOriginalEnd = resp.end;
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resp._wrappedHeaders = [];
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resp._wrappedTransformHtml = transformHtml;
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resp._hasEnded = false;
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resp._shouldForceEnd = false;
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// Compatibility with web standards Response()
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Object.defineProperty(resp, "body", {
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// Returns write cache
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get: function() {
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if(typeof this._writeCache === "string") {
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return this._writeCache;
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}
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},
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// Usage:
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// res.body = ""; // overwrite existing content
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// res.body += ""; // append to existing content, can also res.write("") to append
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set: function(data) {
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if(typeof data === "string") {
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this._writeCache = data;
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}
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}
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});
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// Compatibility with web standards Response()
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Object.defineProperty(resp, "bodyUsed", {
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get: function() {
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return this._hasEnded;
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}
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})
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// Original signature writeHead(statusCode[, statusMessage][, headers])
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resp.writeHead = function(statusCode, ...args) {
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let headers = args[args.length - 1];
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// statusMessage is a string
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if(typeof headers !== "string") {
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this._contentType = getContentType(headers);
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}
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if((this._contentType || "").startsWith("text/html")) {
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this._wrappedHeaders.push([statusCode, ...args]);
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} else {
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return this._wrappedOriginalWriteHead(statusCode, ...args);
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}
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return this;
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}
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// data can be a String or Buffer
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resp.write = function(data, ...args) {
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if(typeof data === "string") {
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if(!this._writeCache) {
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this._writeCache = "";
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}
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// TODO encoding and callback args
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this._writeCache += data;
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} else {
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// Buffers
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return this._wrappedOriginalWrite(data, ...args);
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}
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return this;
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}
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// data can be a String or Buffer
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resp.end = function(data, encoding, callback) {
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resp._hasEnded = true;
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if(typeof this._writeCache === "string" || typeof data === "string") {
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// Strings
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if(!this._writeCache) {
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this._writeCache = "";
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}
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if(typeof data === "string") {
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this._writeCache += data;
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}
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let result = this._writeCache;
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// Only transform HTML
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// Note the “setHeader versus writeHead” note on https://nodejs.org/api/http.html#responsewriteheadstatuscode-statusmessage-headers
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let contentType = this._contentType || getContentType(this.getHeaders());
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if(contentType && contentType.startsWith("text/html")) {
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if(this._wrappedTransformHtml && typeof this._wrappedTransformHtml === "function") {
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result = this._wrappedTransformHtml(result);
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this.setHeader("Content-Length", Buffer.byteLength(result));
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}
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}
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for(let headers of this._wrappedHeaders) {
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this._wrappedOriginalWriteHead(...headers);
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}
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this._writeCache = [];
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this._wrappedOriginalWrite(result, encoding)
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return this._wrappedOriginalEnd(callback);
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} else {
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// Buffers
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for(let headers of this._wrappedHeaders) {
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this._wrappedOriginalWriteHead(...headers);
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}
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if(data) {
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this._wrappedOriginalWrite(data, encoding);
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}
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return this._wrappedOriginalEnd(callback);
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}
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}
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return resp;
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}
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module.exports = wrapResponse; |