Part-DB-server/assets/controllers/elements/nonprintable_char_input_controller.js
2026-03-01 16:48:29 +01:00

106 lines
4.4 KiB
JavaScript

/*
* This file is part of Part-DB (https://github.com/Part-DB/Part-DB-symfony).
*
* Copyright (C) 2019 - 2026 Jan Böhmer (https://github.com/jbtronics)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published
* by the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
import {Controller} from "@hotwired/stimulus";
/**
* Purpose of this controller is to allow users to input non-printable characters like EOT, FS, etc. in a form field and submit them correctly with the form.
* The visible input field encodes non-printable characters via their Unicode Control picture representation, e.g. \n becomes ␊ and \t becomes ␉, so that they can be displayed in the input field without breaking the form submission.
* The actual value of the field, which is submitted with the form, is stored in a hidden input and contains the non-printable characters in their original form.
*/
export default class extends Controller {
_hiddenInput;
connect() {
this.element.addEventListener("input", this._update.bind(this));
// We use a hidden input to store the actual value of the field, which is submitted with the form.
// The visible input is just for user interaction and can contain non-printable characters, which are not allowed in the hidden input.
this._hiddenInput = document.createElement("input");
this._hiddenInput.type = "hidden";
this._hiddenInput.name = this.element.name;
this.element.removeAttribute("name");
this.element.parentNode.insertBefore(this._hiddenInput, this.element.nextSibling);
this.element.addEventListener("keypress", this._onKeyPress.bind(this));
}
/**
* Ensures that non-printable characters like EOT, FS, etc. gets added to the input value when the user types them
* @param event
* @private
*/
_onKeyPress(event) {
const ALLOWED_INPUT_CODES = [4, 28, 29, 30, 31]; //EOT, FS, GS, RS, US
if (!ALLOWED_INPUT_CODES.includes(event.keyCode)) {
return;
}
event.preventDefault();
const char = String.fromCharCode(event.keyCode);
this.element.value += char;
this._update();
}
_update() {
//Chrome workaround: Remove a leading ∠ character (U+2220) that appears when the user types a non-printable character at the beginning of the input field.
if (this.element.value.startsWith("∠")) {
this.element.value = this.element.value.substring(1);
}
// Remove non-printable characters from the input value and store them in the hidden input
const normalizedValue = this.decodeNonPrintableChars(this.element.value);
this._hiddenInput.value = normalizedValue;
// Encode non-printable characters in the visible input to their Unicode Control picture representation
const encodedValue = this.encodeNonPrintableChars(normalizedValue);
if (encodedValue !== this.element.value) {
this.element.value = encodedValue;
}
}
/**
* Encodes non-printable characters in the given string via their Unicode Control picture representation, e.g. \n becomes ␊ and \t becomes ␉.
* This allows us to display non-printable characters in the input field without breaking the form submission.
* @param str
*/
encodeNonPrintableChars(str) {
return str.replace(/[\x00-\x1F\x7F]/g, (char) => {
const code = char.charCodeAt(0);
return String.fromCharCode(0x2400 + code);
});
}
/**
* Decodes the Unicode Control picture representation of non-printable characters back to their original form, e.g. ␊ becomes \n and ␉ becomes \t.
* @param str
*/
decodeNonPrintableChars(str) {
return str.replace(/[\u2400-\u241F\u2421]/g, (char) => {
const code = char.charCodeAt(0) - 0x2400;
return String.fromCharCode(code);
});
}
}