45 lines
1.3 KiB
JavaScript
45 lines
1.3 KiB
JavaScript
'use strict';
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var typeOf = require('kind-of');
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/**
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* Basic sort algorithm that has similar behavior to `Array.prototype.sort`
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* for null and undefined, but also allows sorting by an object property.
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*
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* @param {Mixed} `a` First value to compare.
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* @param {Mixed} `b` Second value to compare.
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* @param {String} `prop` Optional property to use when comparing objects. If specified must be a string.
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* @return {Number} Returns 1 when `a` should come after `b`, -1 when `a` should come before `b`, and 0 when `a` and `b` are equal.
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* @api public
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*/
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module.exports = function defaultCompare(a, b, prop) {
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if (prop != null && typeOf(prop) !== 'string') {
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throw new TypeError('expected "prop" to be undefined or a string');
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}
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var typeA = typeOf(a);
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var typeB = typeOf(b);
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if (prop) {
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if (typeA === 'object') {
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a = a[prop];
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typeA = typeOf(a);
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}
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if (typeB === 'object') {
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b = b[prop];
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typeB = typeOf(b);
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}
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}
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if (typeA === 'null') {
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return typeB === 'null' ? 0 : (typeB === 'undefined' ? -1 : 1);
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} else if (typeA === 'undefined') {
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return typeB === 'null' ? 1 : (typeB === 'undefined' ? 0 : 1);
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} else if (typeB === 'null' || typeB === 'undefined') {
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return -1;
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} else {
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return a < b ? -1 : (a > b ? 1 : 0);
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}
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};
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