JavaScript初学者应注意的七个细节

var car = new Object();
car.colour = 'red';
car.wheels = 4;
car.hubcaps = 'spinning';
car.age = 4;

var car = {
	colour:'red',
	wheels:4,
　　hubcaps:'spinning',
　　age:4
}

var moviesThatNeedBetterWriters = new Array(
  'Transformers','Transformers2','Avatar','Indiana Jones 4'
);

var moviesThatNeedBetterWriters = [
  'Transformers','Transformers2','Avatar','Indiana Jones 4'
];

var car = new Array();
car['colour'] = 'red';
car['wheels'] = 4;
car['hubcaps'] = 'spinning';
car['age'] = 4;

var direction;
if(x < 200){
  direction = 1;
} else {
  direction = -1;
}

var direction = x < 200 ? 1 : -1;

伟大的Douglas Crockford发明了JSON数据格式来存储数据，你可以使用原生的javascript方法来存储复杂的数据而不需要进行任何额外的转换，例如：

var band = {
  "name":"The Red Hot Chili Peppers",
  "members":[
    {
      "name":"Anthony Kiedis",
      "role":"lead vocals"
    },
    {
      "name":"Michael 'Flea' Balzary",
      "role":"bass guitar, trumpet, backing vocals"
    },
    {
      "name":"Chad Smith",
      "role":"drums,percussion"
    },
    {
      "name":"John Frusciante",
      "role":"Lead Guitar"
    }
  ],
  "year":"2009"
}

你可以使用在JavaScript中直接使用JSON，甚至作为API返回的一种格式，这就是所谓的JSON – P，在许多的API中被应用，例如：

<div id="delicious"></div><script>
function delicious(o){
  var out = '<ul>';
  for(var i=0;i<o.length;i++){
    out += '<li><a href="' + o[i].u + '">' +
           o[i].d + '</a></li>';
  }
  out += '</ul>';
  document.getElementById('delicious').innerHTML = out;
}
</script>
<script src="http://feeds.delicious.com/v2/json/codepo8/javascript?count=15&callback=delicious"></script>

var numbers = [3,342,23,22,124];
numbers.sort(function(a,b){return b - a});
alert(numbers[0]);

Math.max(12,123,3,2,433,4); // returns 433

var scrollTop= Math.max(
 doc.documentElement.scrollTop,
 doc.body.scrollTop
);

function addclass(elm,newclass){
  var c = elm.className;
  elm.className = (c === '') ? newclass : c+' '+newclass;

function addclass(elm,newclass){
  var classes = elm.className.split(' ');
  classes.push(newclass);
  elm.className = classes.join(' ');
}

<h2>Great Web resources</h2>
<ul id="resources">
  <li><a href="http://opera.com/wsc">Opera Web Standards Curriculum</a></li>
  <li><a href="http://sitepoint.com">Sitepoint</a></li>
  <li><a href="http://alistapart.com">A List Apart</a></li>
  <li><a href="http://yuiblog.com">YUI Blog</a></li>
  <li><a href="http://blameitonthevoices.com">Blame it on the voices</a></li>
  <li><a href="http://oddlyspecific.com">Oddly specific</a></li>
</ul>

// Classic event handling example
(function(){
  var resources = document.getElementById('resources');
  var links = resources.getElementsByTagName('a');
  var all = links.length;
  for(var i=0;i<all;i++){
    // Attach a listener to each link
    links[i].addEventListener('click',handler,false);
  };
  function handler(e){
    var x = e.target; // Get the link that was clicked
    alert(x);
    e.preventDefault();
  };
})();

(function(){
  var resources = document.getElementById('resources');
  resources.addEventListener('click',handler,false);
  function handler(e){
    var x = e.target; // get the link tha
    if(x.nodeName.toLowerCase() === 'a'){
      alert('Event delegation:' + x);
      e.preventDefault();
    }
  };
})();

var name = 'Chris';
var age = '34';
var status = 'single';
function createMember(){
  // [...]
}
function getMemberDetails(){
  // [...]
}

var myApplication = function(){
  var name = 'Chris';
  var age = '34';
  var status = 'single';
  return{
    createMember:function(){
      // [...]
    },
    getMemberDetails:function(){
      // [...]
    }
  }
}();
// myApplication.createMember() and
// myApplication.getMemberDetails() now works.

var myApplication = function(){
  var name = 'Chris';
  var age = '34';
  var status = 'single';
  function createMember(){
    // [...]
  }
  function getMemberDetails(){
    // [...]
  }
  return{
    create:createMember,
    get:getMemberDetails
  }
}();
//myApplication.get() and myApplication.create() now work.