Prototype Array对象 学习
2024-05-06 14:14:48
供稿：网友
代码如下:
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];
