123 lines
3.6 KiB
Plaintext
123 lines
3.6 KiB
Plaintext
/**
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* Copyright (c) 2013-present, Facebook, Inc.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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* @providesModule createArrayFromMixed
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* @typechecks
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*/
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const invariant = require('./invariant');
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/**
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* Convert array-like objects to arrays.
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*
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* This API assumes the caller knows the contents of the data type. For less
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* well defined inputs use createArrayFromMixed.
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*
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* @param {object|function|filelist} obj
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* @return {array}
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*/
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function toArray(obj) {
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const length = obj.length;
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// Some browsers builtin objects can report typeof 'function' (e.g. NodeList
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// in old versions of Safari).
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invariant(!Array.isArray(obj) && (typeof obj === 'object' || typeof obj === 'function'), 'toArray: Array-like object expected');
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invariant(typeof length === 'number', 'toArray: Object needs a length property');
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invariant(length === 0 || length - 1 in obj, 'toArray: Object should have keys for indices');
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invariant(typeof obj.callee !== 'function', 'toArray: Object can\'t be `arguments`. Use rest params ' + '(function(...args) {}) or Array.from() instead.');
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// Old IE doesn't give collections access to hasOwnProperty. Assume inputs
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// without method will throw during the slice call and skip straight to the
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// fallback.
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if (obj.hasOwnProperty) {
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try {
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return Array.prototype.slice.call(obj);
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} catch (e) {
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// IE < 9 does not support Array#slice on collections objects
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}
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}
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// Fall back to copying key by key. This assumes all keys have a value,
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// so will not preserve sparsely populated inputs.
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const ret = Array(length);
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for (let ii = 0; ii < length; ii++) {
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ret[ii] = obj[ii];
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}
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return ret;
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}
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/**
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* Perform a heuristic test to determine if an object is "array-like".
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*
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* A monk asked Joshu, a Zen master, "Has a dog Buddha nature?"
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* Joshu replied: "Mu."
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*
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* This function determines if its argument has "array nature": it returns
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* true if the argument is an actual array, an `arguments' object, or an
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* HTMLCollection (e.g. node.childNodes or node.getElementsByTagName()).
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*
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* It will return false for other array-like objects like Filelist.
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*
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* @param {*} obj
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* @return {boolean}
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*/
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function hasArrayNature(obj) {
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return (
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// not null/false
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!!obj && (
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// arrays are objects, NodeLists are functions in Safari
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typeof obj == 'object' || typeof obj == 'function') &&
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// quacks like an array
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'length' in obj &&
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// not window
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!('setInterval' in obj) &&
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// no DOM node should be considered an array-like
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// a 'select' element has 'length' and 'item' properties on IE8
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typeof obj.nodeType != 'number' && (
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// a real array
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Array.isArray(obj) ||
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// arguments
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'callee' in obj ||
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// HTMLCollection/NodeList
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'item' in obj)
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);
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}
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/**
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* Ensure that the argument is an array by wrapping it in an array if it is not.
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* Creates a copy of the argument if it is already an array.
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*
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* This is mostly useful idiomatically:
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*
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* var createArrayFromMixed = require('createArrayFromMixed');
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*
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* function takesOneOrMoreThings(things) {
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* things = createArrayFromMixed(things);
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* ...
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* }
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*
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* This allows you to treat `things' as an array, but accept scalars in the API.
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*
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* If you need to convert an array-like object, like `arguments`, into an array
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* use toArray instead.
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*
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* @param {*} obj
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* @return {array}
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*/
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function createArrayFromMixed(obj) {
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if (!hasArrayNature(obj)) {
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return [obj];
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} else if (Array.isArray(obj)) {
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return obj.slice();
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} else {
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return toArray(obj);
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}
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}
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module.exports = createArrayFromMixed; |