38 lines
1.5 KiB
JavaScript
38 lines
1.5 KiB
JavaScript
import getLength from './_getLength.js';
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import isFunction from './isFunction.js';
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import allKeys from './allKeys.js';
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// Since the regular `Object.prototype.toString` type tests don't work for
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// some types in IE 11, we use a fingerprinting heuristic instead, based
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// on the methods. It's not great, but it's the best we got.
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// The fingerprint method lists are defined below.
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export function ie11fingerprint(methods) {
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var length = getLength(methods);
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return function(obj) {
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if (obj == null) return false;
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// `Map`, `WeakMap` and `Set` have no enumerable keys.
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var keys = allKeys(obj);
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if (getLength(keys)) return false;
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for (var i = 0; i < length; i++) {
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if (!isFunction(obj[methods[i]])) return false;
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}
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// If we are testing against `WeakMap`, we need to ensure that
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// `obj` doesn't have a `forEach` method in order to distinguish
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// it from a regular `Map`.
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return methods !== weakMapMethods || !isFunction(obj[forEachName]);
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};
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}
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// In the interest of compact minification, we write
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// each string in the fingerprints only once.
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var forEachName = 'forEach',
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hasName = 'has',
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commonInit = ['clear', 'delete'],
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mapTail = ['get', hasName, 'set'];
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// `Map`, `WeakMap` and `Set` each have slightly different
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// combinations of the above sublists.
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export var mapMethods = commonInit.concat(forEachName, mapTail),
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weakMapMethods = commonInit.concat(mapTail),
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setMethods = ['add'].concat(commonInit, forEachName, hasName);
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