polymer/lib/utils/case-map.js

/**
@license
Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
Code distributed by Google as part of the polymer project is also
subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
*/
import './boot.js';

const caseMap = {};
const DASH_TO_CAMEL = /-[a-z]/g;
const CAMEL_TO_DASH = /([A-Z])/g;

/**
 * @fileoverview Module with utilities for converting between "dash-case" and
 * "camelCase" identifiers.
 */

/**
 * Converts "dash-case" identifier (e.g. `foo-bar-baz`) to "camelCase"
 * (e.g. `fooBarBaz`).
 *
 * @param {string} dash Dash-case identifier
 * @return {string} Camel-case representation of the identifier
 */
export function dashToCamelCase(dash) {
  return caseMap[dash] || (
    caseMap[dash] = dash.indexOf('-') < 0 ? dash : dash.replace(DASH_TO_CAMEL,
      (m) => m[1].toUpperCase()
    )
  );
}

/**
 * Converts "camelCase" identifier (e.g. `fooBarBaz`) to "dash-case"
 * (e.g. `foo-bar-baz`).
 *
 * @param {string} camel Camel-case identifier
 * @return {string} Dash-case representation of the identifier
 */
export function camelToDashCase(camel) {
  return caseMap[camel] || (
    caseMap[camel] = camel.replace(CAMEL_TO_DASH, '-$1').toLowerCase()
  );
}