JS basic data type common method extension

1. Contains method for array

The array does not have a contains method, in reality the scenario is that sometimes we need to determine whether a value is

In this array, this time a contains method is very necessary, specifically implemented as follows:

Determine if an element is contained in an array

Array.prototype.contains = function (obj) {

var i = this.length;

while (i--) {

if (this[i] = = = obj) {

return true;

}

}

return false;

}

2. Contains method of string

The same problem also exists in the string type, in JS also has no one to determine whether a substring is wrapped

The method contained in the parent string is implemented as follows:

Whether the string contains a string

String.prototype.contains = function contains (string, substr, isignorecase) {

if (isignorecase) {

this = This.tolowercase ();

string = String.tolowercase ();

substr = Substr.tolowercase ();

}

var Startchar = substr.substring (0, 1);

var strLen = substr.length;

for (var j = 0; J < String.length-strlen + 1; j + +) {

if (String.charat (j) = = Startchar)//

{

if (String.substring (J, j + strLen) = = substr)//

{

return true;

}

}

}

return false;

}

3. Date AddDays, addMonths, Addyear, Format method

Familiar with C # friends, will be very familiar with and enjoy a series of convenient operation of the DateTime, in JS and

There is no time-related operation as convenient as in C #, and sometimes the associated interactions such as the addition and subtraction of time are used, and the date type is extended specifically as follows:

Add Days

Date.prototype.addDays = function (d) {

This.setdate (This.getdate () + D);

};

Add Week

Date.prototype.addWeeks = function (w) {

This.adddays (W * 7);

};

Add month

Date.prototype.addMonths = function (m) {

var d = this.getdate ();

This.setmonth (This.getmonth () + M);

if (This.getdate () < D)

This.setdate (0);

};

Add year

Date.prototype.addYears = function (y) {

var m = This.getmonth ();

This.setfullyear (This.getfullyear () + y);

if (M < This.getmonth ()) {

This.setdate (0);

}

};

Format processing of dates

Date formatting

Date.prototype.Format = function (FMT) {//author:meizz

var o = {

"m+": This.getmonth () + 1,//month

"D+": this.getdate (),//day

"H +": this.gethours (),//hour

"m+": this.getminutes (),//min

"S+": This.getseconds (),//sec

"q+": Math.floor ((This.getmonth () + 3)/3),//Quarterly

"S": this.getmilliseconds ()//MS

};

if (/(y+)/.test (FMT))

FMT = Fmt.replace (regexp.$1, (this.getfullyear () + ""). substr (4-regexp.$1.length));

For (var k in O)

if (New RegExp ("(" + K + ")"). Test (FMT))

FMT = Fmt.replace (regexp.$1, (regexp.$1.length = = 1)? (O[k]): (("XX" + o[k]). substr (("" + O[k]).));

return FMT;

};

4. Math.max.apply (Null,array), find the maximum value in the array

This method is mainly used to find the maximum value in an array, which is often encountered in the actual work. Or

A friend asked, why not call the Math.max () method directly? It is important to note that the Math.max () method supports the passing of multiple parameters, but it does not support passing an array directly as a parameter, but all functions have a method such as apply (scope, parameter), and we use the Apply method to indirectly set the array as an argument. And each value in the array is taken apart to pass to the Max method, thus achieving the need to find the maximum value.