92 lines
3.6 KiB
JavaScript
92 lines
3.6 KiB
JavaScript
/**
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* Sets specific properties of a specific state to specific values and prevents
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* unnecessary state changes.
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*
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* @param {Object} target - The state on which the specified properties are to
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* be set.
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* @param {Object} source - The map of properties to values which are to be set
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* on the specified target.
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* @returns {Object} The specified target if the values of the specified
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* properties equal the specified values; otherwise, a new state constructed
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* from the specified target by setting the specified properties to the
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* specified values.
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*/
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export function setStateProperties(target, source) {
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let t = target;
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for (const property in source) { // eslint-disable-line guard-for-in
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t = setStateProperty(t, property, source[property], t === target);
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}
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return t;
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}
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/**
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* Sets a specific property of a specific state to a specific value. Prevents
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* unnecessary state changes (when the specified <tt>value</tt> is equal to the
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* value of the specified <tt>property</tt> of the specified <tt>state</tt>).
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*
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* @param {Object} state - The (Redux) state from which a new state is to be
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* constructed by setting the specified <tt>property</tt> to the specified
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* <tt>value</tt>.
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* @param {string} property - The property of <tt>state</tt> which is to be
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* assigned the specified <tt>value</tt> (in the new state).
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* @param {*} value - The value to assign to the specified <tt>property</tt>.
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* @returns {Object} The specified <tt>state</tt> if the value of the specified
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* <tt>property</tt> equals the specified <tt>value/tt>; otherwise, a new state
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* constructed from the specified <tt>state</tt> by setting the specified
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* <tt>property</tt> to the specified <tt>value</tt>.
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*/
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export function setStateProperty(state, property, value) {
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return _setStateProperty(state, property, value, /* copyOnWrite */ true);
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}
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/* eslint-disable max-params */
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/**
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* Sets a specific property of a specific state to a specific value. Prevents
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* unnecessary state changes (when the specified <tt>value</tt> is equal to the
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* value of the specified <tt>property</tt> of the specified <tt>state</tt>).
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*
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* @param {Object} state - The (Redux) state from which a state is to be
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* constructed by setting the specified <tt>property</tt> to the specified
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* <tt>value</tt>.
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* @param {string} property - The property of <tt>state</tt> which is to be
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* assigned the specified <tt>value</tt>.
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* @param {*} value - The value to assign to the specified <tt>property</tt>.
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* @param {boolean} copyOnWrite - If the specified <tt>state</tt> is to not be
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* modified, <tt>true</tt>; otherwise, <tt>false</tt>.
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* @returns {Object} The specified <tt>state</tt> if the value of the specified
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* <tt>property</tt> equals the specified <tt>value/tt> or <tt>copyOnWrite</tt>
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* is truthy; otherwise, a new state constructed from the specified
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* <tt>state</tt> by setting the specified <tt>property</tt> to the specified
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* <tt>value</tt>.
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*/
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function _setStateProperty(state, property, value, copyOnWrite) {
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// Delete state properties that are to be set to undefined. (It is a matter
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// of personal preference, mostly.)
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if (typeof value === 'undefined'
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&& Object.prototype.hasOwnProperty.call(state, property)) {
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const newState = copyOnWrite ? { ...state } : state;
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if (delete newState[property]) {
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return newState;
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}
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}
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if (state[property] !== value) {
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if (copyOnWrite) {
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return {
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...state,
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[property]: value
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};
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}
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state[property] = value;
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}
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return state;
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}
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/* eslint-enable max-params */
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