Paul Dariye dariye

Jest Mock Any Property on Window Utility - with automatic cleanup.

Infinite lists and reflow

In my experience, infinite lists use two basic layout strategies. The first uses absolute positioning to control where visible items are rendered. The second uses relative positioning (with top/left padding to offset for unrendered items).

In both cases, the list abstraction caches some metadata about the size of items once they have been rendered– so that it knows where to position the items that come after them.

Both of these strategies need to handle reflow. For example, changing the width of a list often affects the height of its itesm. Generally speaking, only the "window" of rendered (visible) items are remeasured in this case (because it would be too slow to rerender and remeasure all of the items before). But once a user scrolls backwards (up/left)– the list needs to account for the reflowed sizes. If it didn't, items would appear to jump up or down (depending on the delta between the previous, cached sizes and the new/reflowed sizes).

How the list deals with new sizes

I've been deceiving you all. I had you believe that Svelte was a UI framework — unlike React and Vue etc, because it shifts work out of the client and into the compiler, but a framework nonetheless.

But that's not exactly accurate. In my defense, I didn't realise it myself until very recently. But with Svelte 3 around the corner, it's time to come clean about what Svelte really is.

Svelte is a language.

Specifically, Svelte is an attempt to answer a question that many people have asked, and a few have answered: what would it look like if we had a language for describing reactive user interfaces?

A few projects that have answered this question:

Moved to Shopify/graphql-design-tutorial

Note:

When this guide is more complete, the plan is to move it into Prepack documentation.
For now I put it out as a gist to gather initial feedback.

A Gentle Introduction to Prepack (Part 1)

If you're building JavaScript apps, you might already be familiar with some tools that compile JavaScript code to equivalent JavaScript code:

Babel lets you use newer JavaScript language features, and outputs equivalent code that targets older JavaScript engines.

	<!DOCTYPE html>
	<html lang="en">

	<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>My Angular from Scratch</title>
	<style>
	.my-component {
	font-family: Arial, sans-serif;

	{
	"context-hook": {
	"prefix": "context",
	"body": [
	"import React, {useState, createContext, useContext} from 'react'",
	"",
	"interface ${1/(.*)/${1:/capitalize}/}ContextAPI {",
	" $1: number",
	" set${1/(.*)/${1:/capitalize}/}: (data: number) => void",
	"}",

	"use strict";

	// Load plugins
	const autoprefixer = require("autoprefixer");
	const browsersync = require("browser-sync").create();
	const cp = require("child_process");
	const cssnano = require("cssnano");
	const del = require("del");
	const eslint = require("gulp-eslint");
	const gulp = require("gulp");

	# THIS FILE HAS BEEN AUTO-GENERATED BY THE "GRAPHCOOL DEPLOY"
	# DO NOT EDIT THIS FILE DIRECTLY

	#
	# Model Types
	#

	type User implements Node {
	id: ID!
	name: String!

	import React, { PropTypes } from 'react';
	import styled from 'styled-components'

	const Wrapper = styled.div`
	// styles here that used to be for .test
	`

	const Label = styled.label`
	// label styles here
	`