rauschma

Cheat sheet: Arrays

JavaScript Arrays are a very flexible data structure and used as lists, stacks, queues, tuples (e.g. pairs), etc. Some

Using Arrays

Creating Arrays, reading and writing elements:

chengsokdara

// Author: Sokdara Cheng
// Contact me for web or mobile app development using React or React Native
// https://chengsokdara.github.io
import React, { createContext, useContext, useReducer } from "react";
import initialState from "./initialState"; // object of initial states
import reducer from "./reducer"; // https://reactjs.org/docs/hooks-reference.html#usereducer
const Store = createContext({
  dispatch: () => null,
  state: initialState,
});

hanayashiki

(function () {
  File.prototype.arrayBuffer = File.prototype.arrayBuffer || myArrayBuffer;
  Blob.prototype.arrayBuffer = Blob.prototype.arrayBuffer || myArrayBuffer;

  function myArrayBuffer() {
    // this: File or Blob
    return new Promise((resolve) => {
      let fr = new FileReader();
      fr.onload = () => {
        resolve(fr.result);

lski

/**
 * Shorthand function for document.createElement. Accepts and appends attributes to the newly created element and appends child element, if any.
 * @param tagName The name of the element eg. a or script
 * @param attributes Any additional attributes to add to the element after creating. Eg. href
 * @param children Any child elements you want appended on creating this element, obviously they could be createElement calls as well
 */
export function createElement(tagName, attributes, children) {
    const ele = attributes === (void 0)
        ? document.createElement(tagName)
        : Object.assign(document.createElement(tagName), attributes);

javilobo8

axios({
  url: 'http://localhost:5000/static/example.pdf',
  method: 'GET',
  responseType: 'blob', // important
}).then((response) => {
  const url = window.URL.createObjectURL(new Blob([response.data]));
  const link = document.createElement('a');
  link.href = url;
  link.setAttribute('download', 'file.pdf');
  document.body.appendChild(link);

paulirish

What forces layout / reflow

All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.

Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.

Element APIs

Getting box metrics

• elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent

rxaviers

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