Ruffy javascript study notes_basic knowledge

1. JavaScript prototype model: prototype When implementing object-oriented, (such as when defining a class), a constructor is needed to define the members of the object, and the method is attached to the prototype of the constructor.

2. In JavaScript, in order to implement inheritance, the prototype of the subclass constructor must be set to an object instance of the parent class.

3. CSS block-in-block model:
The outermost margin is used to set the distance from the edge of the space occupied by an element to the adjacent element
Border: border is used to set The connection line of an element
padding is used to set the distance between the element content and the element border
and the background attributes are the content and padding areas, that is, the content and gap
The width and height in the attributes in css refer to It is the width and height of the content area. This is in IE. In Firefox, the above border box must be added.

4, System.Drawing.Imaging.BitmapData..Lock a bitmap into memory..
There are two functions to lock image data into memory
One is: Bitmap.LockBits( Rectangle rect,ImageMode flags,PixelFormat format)
Another one is: Bitmap.LockBits(Rectangle rect,ImageMode flags,PixelFormat format,BimapBitData bitmapData)
bitmapData has an important attribute Scan0, which is a pointer pointing to the picture. The first location in memory where the data is located. Use memory tracking and fill in the value of Scan0 into the address to see the memory allocation.
We can use System.Runtime.InteropServices.Marshal.WriteByte(IntPtr ptr,byte val) to change the pixel value at the specified position.
IntPtr type is called "platform-specific integer type", which is used for native resources, such as window handles.

5, Reflection: Reflection is A process of runtime type discovery. Through reflection, you can get a list of all types contained in a given assembly. This list includes the methods, fields, properties and events defined in the given type. You can also dynamically discover a set of types. The interfaces supported by a given class, method parameters and other related information such as base class, namespace, data list, etc.
for/in statement in javascript:
for(variable in obj)
statement;
One of the most useful features is that it can enumerate all enumerable properties of an object, including native properties and inherited properties, thus providing a very powerful reflection mechanism for JavaScript.
For example:
--for(var each in document.body)
-- document.write(each ":" document.body[each]
);
--//Enumerate and print out all the attributes of the body
variable can be any expression..
For example:
--function keys(obj){
- - var ret= new Array();
-- var i=0;
-- for(ret[i ] in obj)
-- return ret;
-- }
The above function returns the properties of an object as an array.

6,html-table control cellpadding The distance between the content of the cell and the cell
The cellspacing attribute represents the distance between cells
Alignment methods include: align is horizontal alignment with left right center (referring to the horizontal alignment of elements in the cell)
vlign is vertical alignment with top bottom middle

7, Base64 : According to the definition of RFC2045, Base64 is defined as: Base64 content transfer encoding is designed to describe any sequence of 8-bit bytes into a form that is not easy to be directly recognized by humans. (The Base64 Content-Transfer-Encoding is designed to represent arbitrary sequences of octets in a form that need not be humanly readable.)

8,margin:0px auto The upper and lower margins are automatically adjusted to 0px.

9. The difference between opener and self in js: opener refers to . If the current window is opened by the user, the value of opener is null.
self self-reference attribute is a reference to the current window object. The application is synonymous with the window attribute.
(self represents its own window, and opener represents the window that opens itself, such as window A opening window B. If you rely on the window.open method, for window B, self represents B itself, And opener represents window A.)

10,wnd.location.search.slice(1); //Get the string after "?" on the address bar, wnd is a reference to a window object.

11, the meaning of g in the expression
g /global represents global search
i /ignore represents ignoring case
gi combination of the above

12, forward preview And reverse preview
(?=pattern) (?!pattern) non-acquisition, just to check whether the string that appears later is the expected string

13, setcapture mouse capture: mouse capture (setCapture) The function is to capture mouse events to the specified object of the current document. This object receives all mouse events for the current application or the entire system. setCapture captures the following mouse events: onmousedown, onmouseup, onmousemove, onclick, ondblclick, onmouseover, and onmouseout.

14. Using in delete and using objects as collections in JavaScript can easily implement a collection (delete operator deletes the specified object attributes, array elements, or variables. Delete successfully returns true. At the same time, if Returns true even when the operand does not exist)
For example:
---var aSet= new Object();
---sSet["key"]=true; //Insert new element (regardless of Whether it already exists)
---if("key1" in aSet)
--- delete aSet["key1"] //If key1 exists, delete it
---if(delete aSet[" key2"])
--- aSet["key2"]=true; //Delete the original element and update key2

15, -0 and |0 in js can use the former to change a character Implicit conversion to a number, which will round a dotted number.

16,[]: Binary operator for accessing objects and array elements.
When the second operand of [] is an object, first call its toString() method to convert. If the conversion fails, then call the valueOf() method to convert.

17, JavaScript exceptions always propagate upward along the call stack, and events propagate in the same direction.

18, The length attribute of a javascript array can not only be read but also written, setting the length of the array is 0, all elements in the array can be cleared (excluding those array elements whose array subscripts are not integers.)

19, although null and undefined are different, the operator "==" treats them as Equal values ​​(return true)

20, javascript Boxing and unboxing: The operation of converting basic data types to corresponding reference types is called boxing, and conversely, converting reference types to corresponding values Type, is called unboxing.

21, JSON: object constant & array constant
javascript object notation javascript＜object representation method＞
JSON is a simple method developed from javascript Data exchange protocol, its data format is a legal javascript object constant

22, the absolute attribute is combined with left and top to create the relevant "suspended layer" effect. However, sometimes we need a floating effect for a certain container rather than for the window. At this time, calculation of height and width is not only troublesome, but also almost impossible to achieve perfect results. Just set the position of the upper-level style attribute to relative. For example, use div to nest ul and li

23, regarding the movement of DOM elements: use object.appendChild(object.firstChild) to move the first element to the end, but when applied to the table element It moves outside the