【前端基础】基础知识

https://github.com/h5bp/Front-end-Developer-Interview-Questions#contributors

1.　一般性问题　

• What did you learn yesterday/this week?
• What excites or interests you about coding?
• What UI, Security, Performance, SEO, Maintainability or Technology considerations do you make while building a web application or site?
• Talk about your preferred development environment. (OS, Editor or IDE, Browsers, Tools etc.)
• Which version control systems are you familiar with?
• Can you describe your workflow when you create a web page?
• If you have 5 different stylesheets, how would you best integrate them into the site?
  • File concatenation
• Can you describe the difference between progressive enhancement and graceful degradation?
  • Bonus points for describing feature detection
• How would you optimize a websites assets/resources?
  • Looking for a number of solutions which can include:
    • File concatenation
    • File minification
    • CDN Hosted
    • Caching
    • etc.
• Traditionally, why has it been better to serve site assets from multiple domains?
  • How many resources will a browser download from a given domain at a time?
  • What are the exceptions?
    • Bonus points for identifying mobile as a possible downside (http://www.mobify.com/blog/domain-sharding-bad-news-mobile-performance/)
    • Bonus points for identifying HTTP2 / SPDY as an exception
• Name 3 ways to decrease page load. (perceived or actual load time)
• If you jumped on a project and they used tabs and you used spaces, what would you do?
  • Suggest the project utilize something like EditorConfig (http://editorconfig.org)
  • Conform to the conventions (stay consistent)
  • issue :retab! command
• Write a simple slideshow page
  • Bonus points if it does not use JS.
• What tools do you use to test your code's performance?
  • Profiler, JSPerf, Dromaeo
• If you could master one technology this year, what would it be?
• What are the differences between Long-Polling, Websockets and SSE?
• Explain the importance of standards and standards bodies.
• What is FOUC? How do you avoid FOUC?
• Do your best to describe the process from the time you type in a website's URL to it finishing loading on your screen.

2.   HTML相关

• What's a doctype do?
• What's the difference between standards mode and quirks mode?
• What are the limitations when serving XHTML pages?
  • Are there any problems with serving pages as application/xhtml+xml?
• How do you serve a page with content in multiple languages?
  • What kind of things must you be wary of when design or developing for multilingual sites?
• What are data- attributes good for?
• Consider HTML5 as an open web platform. What are the building blocks of HTML5?
• Describe the difference between cookies, sessionStorage and localStorage.
• Can you explain the difference between GET and POST?

3.  CSS相关

• What is the difference between classes and IDs in CSS?
• Describe what a "reset" CSS file does and how it's useful.
  • Bonus for pointing out the downsides of a "reset", and/or mentioning "normalize" as a better alternative.
• Describe Floats and how they work.
• Describe z-index and how stacking context is formed.
• What are the various clearing techniques and which is appropriate for what context?
• Explain CSS sprites, and how you would implement them on a page or site.
• What are your favourite image replacement techniques and which do you use when?
• CSS property hacks, conditionally included .css files, or... something else?
• How do you serve your pages for feature-constrained browsers?
  • What techniques/processes do you use?
• What are the different ways to visually hide content (and make it available only for screen readers)?
• Have you ever used a grid system, and if so, what do you prefer?
• Have you used or implemented media queries or mobile specific layouts/CSS?
• Any familiarity with styling SVG?
• How do you optimize your webpages for print?
• What are some of the "gotchas" for writing efficient CSS?
• What are the advantages/disadvantages of using CSS preprocessors? (SASS, Compass, Stylus, LESS)
  • If so, describe what you like and dislike about the CSS preprocessors you have used.
• How would you implement a web design comp that uses non-standard fonts?
  • Webfonts (font services like: Google Webfonts, Typekit etc.)
• Explain how a browser determines what elements match a CSS selector?
• Explain your understanding of the box model and how you would tell the browser in CSS to render your layout in different box models.
• What does * { box-sizing: border-box; } do? What are its advantages?
• List as many values for the display property that you can remember.
• What's the difference between inline and inline-block?
• What's the difference between a relative, fixed, absolute and statically positioned element?
• What existing CSS frameworks have you used locally, or in production? (Bootstrap, PureCSS, Foundation etc.)
  • If so, which ones? If you could, how would you change/improve them?
• Have you played around with the new CSS Flexbox or Grid specs?
• How is responsive design different from adaptive design?
• Have you ever worked with retina graphics? If so, when and what techniques did you use?

4.  JS 问题

• Explain event delegation
• Explain how this works in JavaScript
• Explain how prototypal inheritance works
• How do you go about testing your JavaScript?
• AMD vs. CommonJS?
• Explain why the following doesn't work as an IIFE: function foo(){ }();.
  • What needs to be changed to properly make it an IIFE?
• What's the difference between a variable that is: null, undefined or undeclared?
  • How would you go about checking for any of these states?
• What is a closure, and how/why would you use one?
• What's a typical use case for anonymous functions?
• How do you organize your code? (module pattern, classical inheritance?)
• What's the difference between host objects and native objects?
• Difference between: function Person(){}, var person = Person(), and var person = new Person()?
• What's the difference between .call and .apply?
• explain Function.prototype.bind?
• When do you optimize your code?
• When would you use document.write()?
  • Most generated ads still utilize document.write() although its use is frowned upon
• What's the difference between feature detection, feature inference, and using the UA string
• Explain AJAX in as much detail as possible
• Explain how JSONP works (and how it's not really AJAX)
• Have you ever used JavaScript templating?
  • If so, what libraries have you used? (Mustache.js, Handlebars etc.)
• Explain "hoisting".
• Describe event bubbling.
• What's the difference between an "attribute" and a "property"?
• Why is extending built in JavaScript objects not a good idea?
• Difference between document load event and document ready event?
• What is the difference between == and ===?
• Explain the same-origin policy with regards to JavaScript.
• Make this work:

duplicate([1,2,3,4,5]); // [1,2,3,4,5,1,2,3,4,5]

• Why is it called a Ternary expression, what does the word "Ternary" indicate?
• What is "use strict";? what are the advantages and disadvantages to using it?
• Create a for loop that iterates up to 100 while outputting "fizz" at multiples of 3, "buzz" at multiples of 5 and "fizzbuzz" at multiples of 3 and 5

6. jQuery 相关

• Explain "chaining".
• Explain "deferreds".
• What are some jQuery specific optimizations you can implement?
• What does .end() do?
• Name 4 different values you can pass to the jQuery method.
  • Selector (string), HTML (string), Callback (function), HTMLElement, object, array, element array, jQuery Object etc.
• What is the difference between .get(), [], and .eq()?

7.  代码

Question: How would you make this work?

add(2, 5); // 7
add(2)(5); // 7

Question: What value is returned from the following statement?

"i'm a lasagna hog".split("").reverse().join("");

Answer: "goh angasal a m'i"

Question: What is the value of window.foo?

( window.foo || ( window.foo = "bar" ) );

Answer: "bar" (only if window.foo was falsey otherwise it will retain its value)

Question: What is the outcome of the two alerts below?

var foo = "Hello"; 
(function() { 
  var bar = " World"; 
  alert(foo + bar); 
})(); 
alert(foo + bar);

Answer: "Hello World" & ReferenceError: bar is not defined

Question: What is the value of foo.length?

var foo = [];
foo.push(1);
foo.push(2);

Answer: 2

8. 开放式问题

• What's a cool thing you've coded recently? What's something you've built that you're proud of?
• What are some things you like about the developer tools you use?
• Do you have any pet projects? What kind?
• What's your favorite feature of Internet Explorer?

9. 其他

• http://programmers.stackexchange.com/questions/46716/what-technical-details-should-a-programmer-of-a-web-application-consider-before
• http://www.nczonline.net/blog/2010/01/05/interviewing-the-front-end-engineer/
• http://css-tricks.com/interview-questions-css/
• http://davidshariff.com/quiz/
• http://davidshariff.com/js-quiz/
• http://blog.sourcing.io/interview-questions
• http://www.toptal.com/javascript/interview-questions
• http://www.sitepoint.com/5-typical-javascript-interview-exercises/
• http://www.sitepoint.com/5-javascript-interview-exercises/
• http://www.sitepoint.com/10-typical-html-interview-exercises/