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Frontend Interview Questions

HTML

Based on the principles of modern web standards, which of the following best describes "Semantic HTML" and its primary importance?

A. It acts as a server-side directive that compiles HTML into binary code for faster execution. B. It refers to using specific HTML markup that reflects the type and meaning of the content (e.g., <article>, <footer>), which is crucial for accessibility and SEO context. C. It is a deprecated method of styling that uses attributes like font-color directly within tags to ensure older browsers can read the text. D. It is a strict validation rule that prevents the page from rendering if tags are not closed properly.

This simple line chart is constructed from a TSV file storing the closing value of AAPL stock over the last few years. The chart employs conventional margins and a number of D3 features:

d3.tsv - load and parse data
d3.time.format - parse dates
d3.time.scale - x-position encoding
d3.scale.linear - y-position encoding
d3.extent - compute domains
d3.svg.axis - display axes
d3.svg.line - display line shape

	#!/usr/bin/env bash
	# vim:set ft=bash ts=4 sw=4 et :
	# shellcheck shell=bash
	# shellcheck disable=SC2317

	## Usage:
	## docker-etc-hosts-install
	## Installs docker container names and IP addresses in /etc/hosts
	## This script is idempotent
	## Note: Requires root privileges to write to /etc/hosts

	class DeferredPromise extends Promise {

	constructor(def = (res, rej)=>{}) {
	let res, rej;
	super((resolve, reject)=>{
	def(resolve, reject);
	res = resolve;
	rej = reject;
	});
	this.resolve = res;

	#!/usr/bin/env bash

	if [ -z "$1" ]
	then
	echo "$0 client-name"
	exit 1
	fi

	#!/bin/bash

	function test {
	MESSAGE=$1
	RECEIVED=$2
	EXPECTED=$3

	if [ "$RECEIVED" = "$EXPECTED" ]; then
	echo -e "\033[32m✔︎ Tested $MESSAGE"
	else

	(function(w, d, undefined){
	if( w.onfocusin === undefined){
	d.addEventListener('focus', addPolyfill, true);
	d.addEventListener('blur', addPolyfill, true);
	d.addEventListener('focusin', removePolyfill, true);
	d.addEventListener('focusout', removePolyfill, true);
	}

	function addPolyfill(e){
	var type = e.type === 'focus' ? 'focusin' : 'focusout';

	<link rel="import" href="../core-input/core-input.html">
	<link rel="import" href="../core-menu-button/core-menu-button.html">
	<link rel="import" href="../core-icons/core-icons.html">
	<link rel="import" href="../core-item/core-item.html">
	<link rel="import" href="../paper-radio-button/paper-radio-button.html">

	<polymer-element name="my-element">

	<template>
	<style>

	function create_guid() {
	$random_bytes = '';

	if (function_exists('mcrypt_create_iv')) {
	$random_bytes .= @mcrypt_create_iv(100, MCRYPT_DEV_URANDOM);
	}

	if (strtoupper(substr(PHP_OS, 0, 3)) !== 'WIN') { // Unix
	if ($fp = @fopen('/dev/urandom','rb')) {
	$random_bytes .= @fread($fp, 100);