polyfills

I stumbled over this polyfill of Array.prototype.includes. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/includes . Is there a reason for the comparison of the variables with themselves on line 21,22? if (searchElement === currentElement || (searchElement !== searchElement && currentElement !== currentElement)) { return true; } Bergi Yes, this second operand of the || does check whether both searchElement and currentElement are NaN - the only value in JavaScript that is not === to itself. includes is supposed to use the SameValueZero equivalence

I am attempting to use an Apollo Client on a node.js server to interface with another GraphQL API using the following code: import fetch from 'node-fetch' import { createHttpLink } from 'apollo-link-http' import ApolloClient from 'apollo-boost' import { API_URL } from '...' const client = new ApolloClient({ link: createHttpLink({ uri: API_URL, fetch: fetch, }), }) Which yields the following error: module initialization error: Error fetch is not found globally and no fetcher passed, to fix pass a fetch for your environment like https://www.npmjs.com/package/node-fetch. For example: import fetch

I'd like to be able to use the ::outside pseudoelement, but apparently none of the major browsers support it (based on my testing today). Is there some kind of JS polyfill that enables this selector? Or is there a good technique for simulating this? You are correct: no browser in existence has implemented any of the new features in the ancient CSS3 Generated and Replaced Content module , so you won't be able to try the proposed pseudo-elements. In fact, they're planning to rewrite the module itself, so the current working draft should be considered abandoned, and unfortunately there's no

Is there a polyfill to handle CSS Background Sizing in Safari 4 (iOS) and IE could try this. http://nooshu.com/jquery-plug-in-scalable-background-image I'm in the process of looking as well. lockedown Allegedly this is a polyfill on GitHUb that enables CSS3 Background Size to work, but I'm still having issues figuring it out myself. https://github.com/louisremi/background-size-polyfill Let me know if you get it to work. I'm looking for something similar. 来源： https://stackoverflow.com/questions/7572432/css-background-sizing-polyfill

I know that when a function returned by Function.prototype.bind is called as a constructor, the pre-bound this is ignored. This is the behaviour specified in ECMA-262, and the behaviour that MDN polyfill implements. My question is: how that polyfill works in that case? I know that this code is responsoble for that: fNOP = function () {} and return fToBind.apply(this instanceof fNOP && oThis ? this : oThis, and fNOP.prototype = this.prototype; fBound.prototype = new fNOP(); But why do they need to create this dummy function ( fNOP ), instantiate it and assign to the fBound 's prototype and so