Javascript personal notes (not organized, very messy)_javascript skills

==============About the display and hiding of elements==============

Visibility is faster than Display

Let Disappearing and appearing pictures can create interesting effects. There are two ways to achieve this: use the CSS visibility attribute or the

display attribute. For absolutely positioned elements, dialog and visibility have the same effect. The difference between the two is that the element set to

display:none will no longer occupy the space of the document flow, while the element set to visibility:hidden will still retain its original position.

==============A little experience=======================

1. JS variables do not have block scope, and the definitions in the judgment loop are defined in the entire function

2. The parameter of split() is a regular string, so if Zheng Ze’s expression is used, it is special Characters must be escaped when used as parameters

============== Hide the toolbar that pops up when the mouse is moved over the image in the browser======== =====



or

==============Some tips==================

1. #Connection will not be returned Go to the top



---------------

2. Close the opener without prompting

=null;

window.close();

============Some summary of js object-oriented programming========== ===

1. Static attribute class instances cannot be accessed. Similarly, instance attributes can only be accessed by instances

var myfun=function(){this.a="a"};

myfun.b="b";

alert(new myfun().a);//Output a

alert(myfun.a);//Output undefined

alert(myfun.b);//Output b

alert(new myfun().b);//Output undefined

2. Add attributes to prototype

The attributes added to prototype will become common attributes of objects created using this constructor.

function Fish(name, color)

{

this.name=name;

this.color=color;

}

Fish.prototype.livesIn="water";

Fish.prototype.price=20;

As the example above shows, each instance of fish can have Different names and colors, but they have one attribute in common, that is, they all live in water.

This is because when an object is created, this constructor will assign its attribute prototype to the internal attribute __proto__ of the new object. This __proto__ is used by this object to find its properties.

3. Use prototype to add functions to objects

Use prototype to add common functions to all objects. This has the advantage that you don't need to create and initialize this function every time you construct an object.

4. Each function has a static name attribute (similarly, each built-in class has a static name attribute). This attribute cannot and will not be overridden

function a() ={};

var b=new Function();

alert(b.name);//Output anonymous

alert(a.name);// Output a

alert(Array.name);//Output Array

================== About this====== =============

The reason why I talk about this is because it is not completely equivalent to the this variable in C++ or Java.

This in js represents a non-prototype extended method that is close to the calling location.

For example, mentioned above

MyObj.prototype.sayBye = function () {

alert(”Bye” this.name);

}

The non-prototype function of this inside this is MyObj (note again that classes in js are implemented through functions), so this.name is an instance variable.

But in this case

MyObj.prototype.doSomething = function () {

todo(function () {

alert(this.name );

});

}

At this time, this represents the anonymous function

function () {

alert(this.name)

}

Then an error will occur here. If you want to use it this way, you should use auxiliary variables.

MyObj.prototype.doSomething = function () {

var me = this; //Assign your reference to the variable me

todo (function () {

alert(me.name); //Access myObj instance through me

});

}