Common JavaScript algorithms and functions

Code usage:

0001:
Determines whether a computing result is infinite: if (isFinite (999999999*999999999) = true)
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0002:
Determine if it is a number: if (isNaN ("Blue") = true), true if it is not a number, false if it is a number.
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0003:
Number hexadecimal conversion:
Var num = 10;
Alert (num. toString () + "<br>"; // decimal
Alert (num. toString (2) + "<br>"; // binary
Alert (num. toString (8) + "<br>"; // octal
Alert (num. toString (16) + "<br>"; // hexadecimal
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0004:
Convert string type to numeric type: note that parseFloat can be selected as decimal if there is no hexadecimal parameter.
Var str = "10 ";
Alert (parseInt (str, 10); // the string is processed in decimal format.
Alert (parseInt (str, 2); // the string is treated as binary.
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0005:
Forced type conversion:
Var str = "10 ";
Var num = new Number (str );
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0006:
Basic Attributes and methods of Object classes: All classes are inherited from objects, so these attributes and methods are available.
Attribute:
● Constructor: a reference to the function used to create an object. Point to the constructor.
● Prototype: Reference to the object Prototype of the object.
Method:
● HasOwnProperty (property): determines whether an object has an attribute.
● IsPrototypeOf (aobject): determines whether the object is a prototype of another object.
● PrototypeIsEnumerable (protype): determines whether attributes can be enumerated using the for... in statement.
● ToString ()
● ValueOf ()
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0007:
Several Methods to declare an array:
Var array1 = new Array ();
Var array2 = new Array ("Blue", "Red", "Black ");
Var array3 = ["Blue", "Red", "Black"];
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0008:
Method for creating the Date type: var myDate = new Date (Date. parse ("2007/1/2 "));
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0009:
URL encoding and decoding:
Var url = new String ("http://www.qpsh.com? Name = smartkernel ");
// Encoding: encode all non-standard characters
Var enUrl = encodeURIComponent (url); // encodeURI (url );
// Decoding: convert to the original format
Var deUrl = decodeURIComponent (enUrl); // decodeURI (enUrl );
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0010:
Encoding and decoding in ASP. Net:
String url = "http://www.126.com? Name = smartkernel ";
String enUrl = this. Server. HtmlEncode (url );
String deUrl = this. Server. HtmlDecode (enUrl );
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0011:
Static Method: JavaScript static function, that is, the function declared to the constructor
Copy codeThe Code is as follows:
Function Person ()
{

}
Person. say = function (msg)
{
Alert (msg );
}
Person. say ("hello ");

0012:
Create an object:
Copy codeThe Code is as follows:
Function Person (name, age)
{
Person. prototype. Name = name;
Person. prototype. Age = age;
// This. Name = name;
// This. Age = age;
}
Person. prototype. say = function ()
{
Alert (this. Name + "|" + this. Age );
}

Var aPerson = new Person ("James", 23 );
APerson. say ();

0013:
Create StringBuilder:
Copy codeThe Code is as follows:
Function StringBuilder ()
{
This. arrayData = new Array ();
}
StringBuilder. prototype. append = function (str)
{
This. arrayData. push (str );
}
StringBuilder. prototype. toString = function ()
{
Return this. arrayData. join ("");
}

Var aStringBuilder = new StringBuilder ();
AStringBuilder. append ("world ");
AStringBuilder. append ("hello ");

Alert (aStringBuilder. toString ());

0014:
Inheritance implementation:
Copy codeThe Code is as follows:
Function Person (name)
{
This. Name = name;
This. sayName = function ()
{
Alert (this. Name );
}
}

Function MyPerson (name, age)
{
This. ctorFun = Person;
This. ctorFun (name );
Delete this. ctorFun;

This. Age = age;
This. sayAge = function ()
{
Alert (this. Age );
}

This. say = function ()
{
Alert (this. Name + "|" + this. Age );
}
}

Var aMyPerson = new MyPerson ("James", 25 );
AMyPerson. sayName ();
AMyPerson. sayAge ();
AMyPerson. say ();

0015:
Inheritance implementation:
Copy codeThe Code is as follows:
Function Person (name)
{
This. Name = name;
This. sayName = function ()
{
Alert (this. Name );
}
}

Function MyPerson (name, age)
{
Person. call (this, name); // or Person. apply (this, new Array (name ));

This. Age = age;
This. sayAge = function ()
{
Alert (this. Age );
}

This. say = function ()
{
Alert (this. Name + "|" + this. Age );
}
}

Var aMyPerson = new MyPerson ("James", 25 );
AMyPerson. sayName ();
AMyPerson. sayAge ();
AMyPerson. say ();

0016:
Multiple inheritance:
Copy codeThe Code is as follows:
Function Person1 (name)
{
This. Name = name;
This. sayName = function ()
{
Alert (this. Name );
}
}
Function Person2 (sex)
{
This. Sex = sex;
This. saySex = function ()
{
Alert (this. sex );
}
}

Function MyPerson (name, age, sex)
{
Person1.call (this, name );
Person2.call (this, sex );

This. Age = age;
This. sayAge = function ()
{
Alert (this. Age );
}

This. say = function ()
{
Alert (this. Name + "|" + this. Age + "|" + this. Sex );
}
}

Var aMyPerson = new MyPerson ("James", 25, "male ");
AMyPerson. say ();

0017:
Implementation of inheritance: The prototype chain method does not support constructors with parameters and multiple inheritance
Copy codeThe Code is as follows:
Function Person ()
{

}

Function MyPerson ()
{

}
MyPerson. prototype = new Person (); // parameters are not allowed

0018:
A reasonable inheritance mechanism is a combination of the above methods:
Copy codeThe Code is as follows:
Function Person (name)
{
This. Name = name;
This. sayName = function ()
{
Alert (this. Name );
}
}

Function MyPerson (name, age)
{
Person. call (this, name); // or Person. apply (this, new Array (name ));

This. Age = age;
This. sayAge = function ()
{
Alert (this. Age );
}

This. say = function ()
{
Alert (this. Name + "|" + this. Age );
}
}
MyPerson. prototype = new Person ();

Var aMyPerson = new MyPerson ("James", 25 );
AMyPerson. sayName ();
AMyPerson. sayAge ();
AMyPerson. say ();

0019:
Error handling:
Copy codeThe Code is as follows:
<Head>
<Script type = "text/Javascript">
Window. onerror = function (msg, url, line)
{
Var err = "error message:" + msg + ". /N "+" error address: "+ url + ". /N "+" error row: "+ line + ". /N ";
Alert (err );
}
</Script>