GetFirst.js

/**
 * @author       Richard Davey <rich@phaser.io>
 * @copyright    2013-2026 Phaser Studio Inc.
 * @license      {@link https://opensource.org/licenses/MIT|MIT License}
 */

var SafeRange = require('./SafeRange');

/**
 * Returns the first element in the array.
 *
 * You can optionally specify a matching criteria using the `property` and `value` arguments.
 *
 * For example: `GetFirst('visible', true)` would return the first element that had its `visible` property set to `true`.
 *
 * Optionally you can specify a start and end index. For example if the array had 100 elements,
 * and you set `startIndex` to 0 and `endIndex` to 50, it would search only the first 50 elements.
 * 
 * You can also specify a negative `startIndex`, such as `-1`, which would start the search at the end of the array
 *
 * You can also specify a negative `startIndex`, such as `-1`, which would start the search at the end of the array
 *
 * @function Phaser.Utils.Array.GetFirst
 * @since 3.4.0
 *
 * @param {array} array - The array to search.
 * @param {string} [property] - The property to test on each array element.
 * @param {*} [value] - The value to test the property against. Must pass a strict (`===`) comparison check.
 * @param {number} [startIndex=0] - An optional start index to search from. You can also set `startIndex` to -1 to start the search from the end of the array.
 * @param {number} [endIndex=array.length] - An optional end index to search up to (but not included)
 *
 * @return {?object} The first matching element from the array, or `null` if no element could be found in the range given.
 */
var GetFirst = function (array, property, value, startIndex, endIndex)
{
    if (startIndex === undefined) { startIndex = 0; }
    if (endIndex === undefined) { endIndex = array.length; }

    var i;
    var child;

    if (startIndex !== -1)
    {
        if (SafeRange(array, startIndex, endIndex))
        {
            for (i = startIndex; i < endIndex; i++)
            {
                child = array[i];

                if (!property ||
                    (property && value === undefined && child.hasOwnProperty(property)) ||
                    (property && value !== undefined && child[property] === value))
                {
                    return child;
                }
            }
        }
    }
    else
        if (SafeRange(array, 0, endIndex))
        {
            for (i = endIndex; i >= 0; i--)
            {
                child = array[i];

                if (!property ||
                    (property && value === undefined && child.hasOwnProperty(property)) ||
                    (property && value !== undefined && child[property] === value))
                {
                    return child;
                }
            }
        }

    return null;
};

module.exports = GetFirst;