生成器和迭代器(仅适用于Firefox 2+和Safari)。

function fib() {
  var i = 0, j = 1;
  while (true) {
    yield i;
    var t = i;
    i = j;
    j += t;
  }
}

var g = fib();
for (var i = 0; i < 10; i++) {
  document.write(g.next() + "<br>\n");
}

The function containing the yield keyword is a generator. When you call it, its formal parameters are bound to actual arguments, but its body isn't actually evaluated. Instead, a generator-iterator is returned. Each call to the generator-iterator's next() method performs another pass through the iterative algorithm. Each step's value is the value specified by the yield keyword. Think of yield as the generator-iterator version of return, indicating the boundary between each iteration of the algorithm. Each time you call next(), the generator code resumes from the statement following the yield. In normal usage, iterator objects are "invisible"; you won't need to operate on them explicitly, but will instead use JavaScript's for...in and for each...in statements to loop naturally over the keys and/or values of objects.

var objectWithIterator = getObjectSomehow();

for (var i in objectWithIterator)
{
  document.write(objectWithIterator[i] + "<br>\n");
}

可以将JavaScript对象绑定为HTML元素属性。

<div id="jsTest">Klick Me</div>
<script type="text/javascript">
    var someVariable = 'I was klicked';
    var divElement = document.getElementById('jsTest');
    // binding function/object or anything as attribute
    divElement.controller = function() { someVariable += '*'; alert('You can change instance data:\n' + someVariable ); };
    var onclickFunct = new Function( 'this.controller();' ); // Works in Firefox and Internet Explorer.
    divElement.onclick = onclickFunct;
</script>

可以使用[]而不是。

这允许您查找与变量匹配的属性。

obj = {a:"test"};
var propname = "a";
var b = obj[propname];  // "test"

您还可以使用此命令获取/设置名称不是合法标识符的对象属性。

obj["class"] = "test";  // class is a reserved word; obj.class would be illegal.
obj["two words"] = "test2"; // using dot operator not possible with the space.

有些人不知道这一点，最终像这样使用eval()，这是一个非常糟糕的主意:

var propname = "a";
var a = eval("obj." + propname);

这更难阅读，更难发现错误(不能使用jslint)，执行速度更慢，并可能导致XSS漏洞。

我可以引用道格拉斯·克罗克福德这本好书的大部分内容 JavaScript:好的部分。

但我只给你一个，总是使用===和!==而不是==和!=

alert('' == '0'); //false
alert(0 == ''); // true
alert(0 =='0'); // true

==是不可传递的。如果你使用===，它会给出false for 所有这些陈述都符合预期。

要正确地从对象中删除一个属性，你应该删除该属性，而不是仅仅将其设置为undefined:

var obj = { prop1: 42, prop2: 43 };

obj.prop2 = undefined;

for (var key in obj) {
    ...

prop2属性仍然是迭代的一部分。如果你想完全摆脱prop2，你应该这样做:

delete obj.prop2;

在遍历属性时，prop2属性将不再出现。

在我的脑海中…

功能

参数。Callee指的是承载“arguments”变量的函数，所以它可以用来递归匿名函数:

var recurse = function() {
  if (condition) arguments.callee(); //calls recurse() again
}

如果你想做这样的事情，这很有用:

//do something to all array items within an array recursively
myArray.forEach(function(item) {
  if (item instanceof Array) item.forEach(arguments.callee)
  else {/*...*/}
})

对象

关于对象成员有一个有趣的事情:他们可以有任何字符串作为他们的名字:

//these are normal object members
var obj = {
  a : function() {},
  b : function() {}
}
//but we can do this too
var rules = {
  ".layout .widget" : function(element) {},
  "a[href]" : function(element) {}
}
/* 
this snippet searches the page for elements that
match the CSS selectors and applies the respective function to them:
*/
for (var item in rules) {
  var elements = document.querySelectorAll(rules[item]);
  for (var e, i = 0; e = elements[i++];) rules[item](e);
}

字符串

字符串。Split可以将正则表达式作为参数:

"hello world   with  spaces".split(/\s+/g);
//returns an array: ["hello", "world", "with", "spaces"]

字符串。Replace可以将正则表达式作为搜索参数，将函数作为替换参数:

var i = 1;
"foo bar baz ".replace(/\s+/g, function() {return i++});
//returns "foo1bar2baz3"