JS_javascript スキルにおける Array オブジェクトの展開と String オブジェクトの展開の詳細な説明

早速、配列オブジェクトの拡張コードを説明します。具体的なコードは次のとおりです。

/**
* Created by laixiangran on 2016/01/07.
* Array扩展
*/
(function() {
// 遍历数组
if (typeof Array.prototype.forEach != "function") {
Array.prototype.forEach = function (fn, context) {
for (var i = 0; i < this.length; i++) {
if (typeof fn === "function" && Object.prototype.hasOwnProperty.call(this, i)) {
fn.call(context, this[i], i, this);
}
}
};
}
// 让数组中的每一个元素调用给定的函数，然后把得到的结果放到新数组中返回
if (typeof Array.prototype.map != "function") {
Array.prototype.map = function (fn, context) {
var arr = [];
if (typeof fn === "function") {
for (var k = 0, length = this.length; k < length; k++) {
arr.push(fn.call(context, this[k], k, this));
}
}
return arr;
};
}
// 把符合条件的元素放到一个新数组中返回
if (typeof Array.prototype.filter != "function") {
Array.prototype.filter = function (fn, context) {
var arr = [];
if (typeof fn === "function") {
for (var k = 0, length = this.length; k < length; k++) {
fn.call(context, this[k], k, this) && arr.push(this[k]);
}
}
return arr;
};
}
// 如果数组中的每个元素都能通过给定的函数的测试，则返回true，反之false
if (typeof Array.prototype.every != "function") {
Array.prototype.every = function (fn, context) {
var passed = true;
if (typeof fn === "function") {
for (var k = 0, length = this.length; k < length; k++) {
if (passed === false) break;
passed = !!fn.call(context, this[k], k, this);
}
}
return passed;
};
}
// 类似every函数，但只要有一个通过给定函数的测试就返回true
if (typeof Array.prototype.some != "function") {
Array.prototype.some = function (fn, context) {
var passed = false;
if (typeof fn === "function") {
for (var k = 0, length = this.length; k < length; k++) {
if (passed === true) break;
passed = !!fn.call(context, this[k], k, this);
}
}
return passed;
};
}
// 返回元素在数组的索引，没有则返回-1，从左到右
if (typeof Array.prototype.indexOf != "function") {
Array.prototype.indexOf = function (item, index) {
var n = this.length,
i = index == null &#63; 0 : index < 0 &#63; Math.max(0, n + index) : index;
for (; i < n; i++) {
if (i in this && this[i] === item) {
return i
}
}
return -1
};
}
// 返回元素在数组的索引，没有则返回-1，从右到左
if (typeof Array.prototype.lastIndexOf != "function") {
Array.prototype.lastIndexOf = function (item, index) {
var n = this.length,
i = index == null &#63; n-1 : index < 0 &#63; Math.max(0, n + index) : index;
for (; i >= 0; i--) {
if (i in this && this[i] === item) {
return i;
}
}
return -1;
};
}
// 让数组元素依次调用给定函数，最后返回一个值（从左到右）
if (typeof Array.prototype.reduce != "function") {
Array.prototype.reduce = function (callback, initialValue) {
var previous = initialValue, k = 0, length = this.length;
if (typeof initialValue === "undefined") {
previous = this[0];
k = 1;
}
if (typeof callback === "function") {
for (k; k < length; k++) {
this.hasOwnProperty(k) && (previous = callback(previous, this[k], k, this));
}
}
return previous;
};
}
// 让数组元素依次调用给定函数，最后返回一个值（从右到左）
if (typeof Array.prototype.reduceRight != "function") {
Array.prototype.reduceRight = function (callback, initialValue) {
var length = this.length, k = length - 1, previous = initialValue;
if (typeof initialValue === "undefined") {
previous = this[length - 1];
k--;
}
if (typeof callback === "function") {
for (k; k > -1; k-=1) {
this.hasOwnProperty(k) && (previous = callback(previous, this[k], k, this));
}
}
return previous;
};
}
// 去掉重复项（唯一性），返回新数组
if (typeof Array.prototype.uniq != "function") {
Array.prototype.uniq = function() {
var arr = [];
arr[0] = this[0];
for (var i = 1; i < this.length; i++) {
if (arr.indexOf(this[i]) == -1) {
arr.push(this[i]);
}
}
return arr;
};
}
// 指定删除数组中某值
if (typeof Array.prototype.remove != "function") {
Array.prototype.remove = function(item) {
for (var i = this.length; i >= 0; i--) {
if (item === this[i]) {
this.splice(i, 1);
}
}
return this;
};
}
// 打乱数组顺序
if (typeof Array.prototype.shuffle != "function") {
Array.prototype.shuffle = function() {
var i = this.length;
while (i) {
var j = Math.floor(Math.random()*i);
var t = this[--i];
this[i] = this[j];
this[j] = t;
}
return this;
};
}
// 求数组的最大值
if (typeof Array.prototype.max != "function") {
Array.prototype.max = function() {
return Math.max.apply({}, this)
};
}
// 求数组的最小值
if (typeof Array.prototype.max != "function") {
Array.prototype.min = function() {
return Math.min.apply({}, this)
};
} 

// 判断是否为数组
if (typeof Array.prototype.isArray != "function") {
Array.prototype.isArray = function() {
return Object.prototype.toString.apply(this) === "[object Array]";
};
} 
}());

以下は文字列オブジェクトの展開コードです:

/**
* Created by laixiangran on 2015/12/12.
* String扩展
*/
(function() {
// 十六进制颜色值的正则表达式
var reg = /^#([0-9a-fA-f]{3}|[0-9a-fA-f]{6})$/;
// RGB颜色转换为16进制
if (typeof String.prototype.rgbToHex != "function") {
String.prototype.rgbToHex = function() {
var that = this;
if (/^(rgb|RGB)/.test(that)) {
var aColor = that.replace(/(?:\(|\)|rgb|RGB)*/g,"").split(",");
var strHex = "#";
for (var i=0; i<aColor.length; i++) {
var hex = Number(aColor[i]).toString(16);
if (hex === "0") {
hex += hex;
}
strHex += hex;
}
if (strHex.length !== 7) {
strHex = that;
}
return strHex;
}else if (reg.test(that)) {
var aNum = that.replace(/#/,"").split("");
if (aNum.length === 6){
return that;
}else if (aNum.length === 3) {
var numHex = "#";
for (var j=0; j<aNum.length; j++) {
numHex += (aNum[j]+aNum[j]);
}
return numHex;
}
}else{
return that;
}
};
}
// 16进制颜色转为RGB格式
if (typeof String.prototype.hexToRgb != "function") {
String.prototype.hexToRgb = function() {
var sColor = this.toLowerCase();
if (sColor && reg.test(sColor)) {
if (sColor.length === 4) {
var sColorNew = "#";
for (var i = 1; i < 4; i++) {
sColorNew += sColor.slice(i,i+1).concat(sColor.slice(i,i+1));
}
sColor = sColorNew;
}
// 处理六位的颜色值
var sColorChange = [];
for (var j=1; j<7; j+=2) {
sColorChange.push(parseInt("0x"+sColor.slice(j,j+2)));
}
return "RGB(" + sColorChange.join(",") + ")";
}else{
return sColor;
}
};
}
// 移除字符串首尾空白
if (typeof String.prototype.trim != "function") {
String.prototype.trim = function() {
return this.replace(/^\s+|\s+$/g, "");
};
}
}());