form-data.helper.js•3.07 kB
import { arrayWrap } from '../helpers';
// This class is partially inspired by https://github.com/form-data/form-data/blob/master/lib/form_data.js
// All credits to their authors.
export class FormDataHelper {
constructor() {
this._boundary = '';
this._chunks = [];
}
bodyAppend(...values) {
const allAsBuffer = values.map(val => val instanceof Buffer ? val : Buffer.from(val));
this._chunks.push(...allAsBuffer);
}
append(field, value, contentType) {
const convertedValue = value instanceof Buffer ? value : value.toString();
const header = this.getMultipartHeader(field, convertedValue, contentType);
this.bodyAppend(header, convertedValue, FormDataHelper.LINE_BREAK);
}
getHeaders() {
return {
'content-type': 'multipart/form-data; boundary=' + this.getBoundary(),
};
}
/** Length of form-data (including footer length). */
getLength() {
return this._chunks.reduce((acc, cur) => acc + cur.length, this.getMultipartFooter().length);
}
getBuffer() {
const allChunks = [...this._chunks, this.getMultipartFooter()];
const totalBuffer = Buffer.alloc(this.getLength());
let i = 0;
for (const chunk of allChunks) {
for (let j = 0; j < chunk.length; i++, j++) {
totalBuffer[i] = chunk[j];
}
}
return totalBuffer;
}
getBoundary() {
if (!this._boundary) {
this.generateBoundary();
}
return this._boundary;
}
generateBoundary() {
// This generates a 50 character boundary similar to those used by Firefox.
let boundary = '--------------------------';
for (let i = 0; i < 24; i++) {
boundary += Math.floor(Math.random() * 10).toString(16);
}
this._boundary = boundary;
}
getMultipartHeader(field, value, contentType) {
// In this lib no need to guess more the content type, octet stream is ok of buffers
if (!contentType) {
contentType = value instanceof Buffer ? FormDataHelper.DEFAULT_CONTENT_TYPE : '';
}
const headers = {
'Content-Disposition': ['form-data', `name="${field}"`],
'Content-Type': contentType,
};
let contents = '';
for (const [prop, header] of Object.entries(headers)) {
// skip nullish headers.
if (!header.length) {
continue;
}
contents += prop + ': ' + arrayWrap(header).join('; ') + FormDataHelper.LINE_BREAK;
}
return '--' + this.getBoundary() + FormDataHelper.LINE_BREAK + contents + FormDataHelper.LINE_BREAK;
}
getMultipartFooter() {
if (this._footerChunk) {
return this._footerChunk;
}
return this._footerChunk = Buffer.from('--' + this.getBoundary() + '--' + FormDataHelper.LINE_BREAK);
}
}
FormDataHelper.LINE_BREAK = '\r\n';
FormDataHelper.DEFAULT_CONTENT_TYPE = 'application/octet-stream';