utils.js 2.5 KB

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  1. /**
  2. * @license Copyright (c) 2003-2017, CKSource - Frederico Knabben. All rights reserved.
  3. * For licensing, see LICENSE.md.
  4. */
  5. /* global console:false */
  6. import EmitterMixin from '../../src/emittermixin';
  7. const utils = {
  8. /**
  9. * Creates an instance inheriting from {@link utils.EmitterMixin} with one additional method `observe()`.
  10. * It allows observing changes to attributes in objects being {@link utils.Observable observable}.
  11. *
  12. * The `observe()` method accepts:
  13. *
  14. * * `{String} observableName` – Identifier for the observable object. E.g. `"Editable"` when
  15. * you observe one of editor's editables. This name will be displayed on the console.
  16. * * `{utils.Observable observable} – The object to observe.
  17. * * `{Array.<String>} filterNames` – Array of propery names to be observed.
  18. *
  19. * Typical usage:
  20. *
  21. * const observer = utils.createObserver();
  22. * observer.observe( 'Editable', editor.editables.current );
  23. *
  24. * // Stop listening (method from the EmitterMixin):
  25. * observer.stopListening();
  26. *
  27. * @returns {Emitter} The observer.
  28. */
  29. createObserver() {
  30. const observer = Object.create( EmitterMixin, {
  31. observe: {
  32. value: function observe( observableName, observable, filterNames ) {
  33. observer.listenTo( observable, 'change', ( evt, propertyName, value, oldValue ) => {
  34. if ( !filterNames || filterNames.includes( propertyName ) ) {
  35. console.log( `[Change in ${ observableName }] ${ propertyName } = '${ value }' (was '${ oldValue }')` );
  36. }
  37. } );
  38. return observer;
  39. }
  40. }
  41. } );
  42. return observer;
  43. },
  44. /**
  45. * Checkes wether observable properties are properly bound to each other.
  46. *
  47. * Syntax given that observable `A` is bound to observables [`B`, `C`, ...]:
  48. *
  49. * assertBinding( A,
  50. * { initial `A` attributes },
  51. * [
  52. * [ B, { new `B` attributes } ],
  53. * [ C, { new `C` attributes } ],
  54. * ...
  55. * ],
  56. * { `A` attributes after [`B`, 'C', ...] changed }
  57. * );
  58. */
  59. assertBinding( observable, stateBefore, data, stateAfter ) {
  60. let key, boundObservable, attrs;
  61. for ( key in stateBefore ) {
  62. expect( observable[ key ] ).to.be.equal( stateBefore[ key ] );
  63. }
  64. // Change attributes of bound observables.
  65. for ( [ boundObservable, attrs ] of data ) {
  66. for ( key in attrs ) {
  67. if ( !boundObservable.hasOwnProperty( key ) ) {
  68. boundObservable.set( key, attrs[ key ] );
  69. } else {
  70. boundObservable[ key ] = attrs[ key ];
  71. }
  72. }
  73. }
  74. for ( key in stateAfter ) {
  75. expect( observable[ key ] ).to.be.equal( stateAfter[ key ] );
  76. }
  77. }
  78. };
  79. export default utils;