Prototype Array对象 学习

Array.from = $A; (function() { 
//Array原型的引用     
var arrayProto = Array.prototype, 
slice = arrayProto.slice, 
     //JS 1.6里面会有原生的forEach方法 
_each = arrayProto.forEach; // use native browser JS 1.6 implementation if available 
function each(iterator) { 
for (var i = 0, length = this.length; i < length; i++) 
iterator(this[i]); 
} 
//如果不是JS1.6，_each设置成对象的each方法 
//这里的_each方法是覆盖了Enuerable里面的_each方法 
if (!_each) _each = each; 
function clear() { 
this.length = 0; 
return this; 
} 
function first() { 
return this[0]; 
} 
function last() { 
return this[this.length - 1]; 
} 
//返回所有Array内不为null的数据 
function compact() { 
return this.select(function(value) { 
return value != null; 
}); 
} 
//把多维数组压成一维数组 
function flatten() { 
return this.inject([], function(array, value) { 
if (Object.isArray(value)) 
return array.concat(value.flatten()); //这里有递归调用 
array.push(value); 
return array; 
}); 
} 
function without() { 
var values = slice.call(arguments, 0); 
return this.select(function(value) { 
return !values.include(value); 
}); 
} 
function reverse(inline) { 
return (inline !== false ? this : this.toArray())._reverse(); 
} 
//返回所有Array内不重复的元素，如果数组是有序的，传入true参数，执行起来会更快 
function uniq(sorted) { 
return this.inject([], function(array, value, index) { 
if (0 == index || (sorted ? array.last() != value : !array.include(value))) 
array.push(value); 
return array; 
}); 
} 
//取两个数组的交集 
function intersect(array) { 
return this.uniq().findAll(function(item) { 
return array.detect(function(value) { return item === value }); 
}); 
} 

function clone() { 
return slice.call(this, 0); 
} 
function size() { 
return this.length; 
} 
function inspect() { 
return '[' + this.map(Object.inspect).join(', ') + ']'; 
} 
function toJSON() { 
var results = []; 
this.each(function(object) { 
var value = Object.toJSON(object); 
if (!Object.isUndefined(value)) results.push(value); 
}); 
return '[' + results.join(', ') + ']'; 
} 
function indexOf(item, i) { 
i || (i = 0); 
var length = this.length; 
if (i < 0) i = length + i; 
for (; i < length; i++) 
if (this[i] === item) return i; 
return -1; 
} 
function lastIndexOf(item, i) { 
i = isNaN(i) ? this.length : (i < 0 ? this.length + i : i) + 1; 
var n = this.slice(0, i).reverse().indexOf(item); 
return (n < 0) ? n : i - n - 1; 
} 
function concat() { 
var array = slice.call(this, 0), item; 
for (var i = 0, length = arguments.length; i < length; i++) { 
item = arguments[i]; 
     //这的第二条件是防止把调用方法的数组元素也一起concat起来 
if (Object.isArray(item) && !('callee' in item)) { 
for (var j = 0, arrayLength = item.length; j < arrayLength; j++) 
array.push(item[j]); 
} else { 
array.push(item); 
} 
} 
return array; 
} 
//mixin Enumerable里面的方法 
Object.extend(arrayProto, Enumerable); 
if (!arrayProto._reverse) 
arrayProto._reverse = arrayProto.reverse; 
Object.extend(arrayProto, { 
_each: _each, 
clear: clear, 
first: first, 
last: last, 
compact: compact, 
flatten: flatten, 
without: without, 
reverse: reverse, 
uniq: uniq, 
intersect: intersect, 
clone: clone, 
toArray: clone, 
size: size, 
inspect: inspect, 
toJSON: toJSON 
}); 
//这个bug网上没搜到，谁知道说一下？ 
var CONCAT_ARGUMENTS_BUGGY = (function() { 
return [].concat(arguments)[0][0] !== 1; 
})(1,2) 
if (CONCAT_ARGUMENTS_BUGGY) arrayProto.concat = concat; 
//检查JS是否原生支持indexOf和lastIndexOf方法，不支持则设置成对象内的方法 
if (!arrayProto.indexOf) arrayProto.indexOf = indexOf; 
if (!arrayProto.lastIndexOf) arrayProto.lastIndexOf = lastIndexOf; 
})();

clear
clone
compact
each
first
flatten
from
indexOf
inspect
last
reduce
reverse
size
toArray
toJSON
uniq
without
下面给出一些方法的例子，简单的方法就不给出例子了。
flatten():

['frank', ['bob', 'lisa'], ['jill', ['tom', 'sally']]].flatten() 
// -> ['frank', 'bob', 'lisa', 'jill', 'tom', 'sally']

reduce():这个方法的意思就是，如果数字里面有一个数据，这直接返回这个数据，否则返回原来的数组
uniq():

['Sam', 'Justin', 'Andrew', 'Dan', 'Sam'].uniq(); 
// -> ['Sam', 'Justin', 'Andrew', 'Dan'] ['Prototype', 'prototype'].uniq(); 
// -> ['Prototype', 'prototype'] because String comparison is case-sensitive

without():

[3, 5, 6, 1, 20].without(3) 
// -> [5, 6, 1, 20] [3, 5, 6, 1, 20].without(20, 6) 
// -> [3, 5, 1]