JavaScript + browser

  • DOM (events, quering) 
  • Multi-threading
  • Client storage
  • Client-server communication
  • Feature detection (IE hell, shims, shivs)

Document Object Model


  • Node.ELEMENT_NODE ==  1
  • Node.TEXT_NODE == 3
  • Node.COMMENT_NODE == 8
  • Node.DOCUMENT_NODE == 9

Quering

  • getElementById
  • getElementsByTagName
  • getElementsByClassName
  • querySelectorAll


Traversing

  • parentNode
  • childNodes, firstChild, lastChild
  • nextSibling, previousSibling

Manipulation

  • id, name, value, href, value
  • style (style.width, style.marginTop)
  • className
  • innerHTML, innerText

Events

  • Register handler                                                                    
    • <button onclick="save()">Save</button>
      var btn = document.getElementByTagName("button");
btn.addEventListiner("click", save, false);
  • Capturing, bubbling
    • Bubbling/capturing can be stopped by event.stopPropagation() 
  • Default element handler (link navigation, selection)
    • event.preventDefault()
  • Code example
  • Standard events (mouse, key, window, form)
  • More events Hammer.js

    Multi-threading

    • Event loop
    • Single thread - no concurrency problem
      • Never blocking, no locks, no sleeps

    Timers


    ANIMATION

    • CSS transition sometimes isn't suitable, 
      setInterval or requestAnimationFrame to the rescue
    • Pause between interval's execution is not constant

    web workers 

    var worker = new Worker('my_task.js');
worker.onmessage = function(event) {
  console.log("Worker said : " + event.data);
};
worker.postMessage('ali');
    my_task.js : 
    postMessage("I'm working befor postMessage('ali').");
onmessage = function(event) {
  postMessage('Hi '+event.data);
};
    • Performing web I/O in the background
    • Dividing tasks among multiple workers

    Client storage

    Cookie

    • HTTP is a stateless protocol
      • Session cookie (no exp date)
      • Persistent cookie
      • HttpOnly cookie
      • Third-party cookie
    • Structure (4KB in total)
      • Name, Value
      • Expiry 
      • Domain, Path 
      • HttpOnly, Secure 
    • Debug

    Local storage

    localStorage.setItem('key', 'value');
var val = localStorage.getItem('key');

    Client-server communication

    Feature detection


    • Can I use?
    • ModernizrJS
    • IE hell
      <!--[if lt IE 9]>
<script src="@Url.Content("~/Scripts/ie/es5-shim.js")"></script>
<script src="@Url.Content("~/Scripts/ie/html5shiv.js")"></script>
<script src="@Url.Content("~/Scripts/ie/respond.js")"></script>
<![endif]-->

    Home task

    • Calculator (digits+-=)
      • Save history


    JavaScript + browser

    By Vladimir Gaevoy

    Made with Slides.com

    JavaScript + browser

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