80 lines
2.1 KiB
JavaScript
80 lines
2.1 KiB
JavaScript
var getTag = require('./_getTag'),
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isArguments = require('./isArguments'),
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isArray = require('./isArray'),
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isArrayLike = require('./isArrayLike'),
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isBuffer = require('./isBuffer'),
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isPrototype = require('./_isPrototype'),
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nativeKeys = require('./_nativeKeys');
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/** `Object#toString` result references. */
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var mapTag = '[object Map]',
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setTag = '[object Set]';
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/** Used for built-in method references. */
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var objectProto = Object.prototype;
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/** Used to check objects for own properties. */
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var hasOwnProperty = objectProto.hasOwnProperty;
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/** Built-in value references. */
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var propertyIsEnumerable = objectProto.propertyIsEnumerable;
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/** Detect if properties shadowing those on `Object.prototype` are non-enumerable. */
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var nonEnumShadows = !propertyIsEnumerable.call({ 'valueOf': 1 }, 'valueOf');
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/**
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* Checks if `value` is an empty object, collection, map, or set.
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*
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* Objects are considered empty if they have no own enumerable string keyed
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* properties.
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*
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* Array-like values such as `arguments` objects, arrays, buffers, strings, or
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* jQuery-like collections are considered empty if they have a `length` of `0`.
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* Similarly, maps and sets are considered empty if they have a `size` of `0`.
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*
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* @static
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* @memberOf _
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* @since 0.1.0
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* @category Lang
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* @param {*} value The value to check.
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* @returns {boolean} Returns `true` if `value` is empty, else `false`.
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* @example
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*
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* _.isEmpty(null);
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* // => true
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*
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* _.isEmpty(true);
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* // => true
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*
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* _.isEmpty(1);
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* // => true
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*
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* _.isEmpty([1, 2, 3]);
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* // => false
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*
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* _.isEmpty({ 'a': 1 });
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* // => false
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*/
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function isEmpty(value) {
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if (isArrayLike(value) &&
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(isArray(value) || typeof value == 'string' ||
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typeof value.splice == 'function' || isBuffer(value) || isArguments(value))) {
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return !value.length;
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}
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var tag = getTag(value);
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if (tag == mapTag || tag == setTag) {
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return !value.size;
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}
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if (nonEnumShadows || isPrototype(value)) {
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return !nativeKeys(value).length;
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}
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for (var key in value) {
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if (hasOwnProperty.call(value, key)) {
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return false;
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}
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}
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return true;
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}
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module.exports = isEmpty;
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