elevation internship

Analysis of JavaScript variable declaration elevation (Hoisting) and javascripthoisting I. Variable declaration escalation Hoisting English ['h has been st most recent] us ['h has been st most recent] N. Lifting and lifting V... Raise (current Word Segmentation of hoist) Let's look at a chestnut. var cc = 'hello';function foo(){ console.log(cc); var cc = 'world'; console.log(cc);}foo();console.log(cc); The output is as follows:undefined,'world' ,'hell

Linux/unzip tusudo Elevation of Privilege without entering a passwordPreface The sudo permission is required for zip packaging during the process of writing an automated packaging script, but it is too troublesome to enter the password each time. Therefore, we will introduce the method for sudo to escalate permissions without entering a password.Modify/etc/sudoers. If our current user is "wzy", add the following statement to the/etc/sudoers file: # N

JavaScript advanced programming describes how to control the size of elements in a page through JS, which involves three pairs of properties: Offset, client area size, scrolling size. I used to see these three pairs of properties, but it wasn't very clear and confusing. So want to write an article to record their own learning harvest, let oneself understand more profound, at the same time also ask your predecessors to help correct their understanding of the wrong place.First the visible size of

1. The constructor is also a general function , and the following creates a constructor.var person=function(name,age,job) { this. name=name; this. age= age; this. job=job; this. sayname=function() { Console.log (this. Name); } }(1) Call by using the constructor function1 var person=New person ("xiaoming", +, "Doctor"); 2 Person.sayname (); // xiaoming(2) using normal function calls1 Person ("Xiaoming", "Doctor"); 2 Window.sayname (); // x

actually: function fn(){} , that is, the function content.Console.log (FN); var function fn () {}; var fn = ' string ';At this point the output is undefined, it is not difficult to understand the above declaration of ascension of the truth.Summarize:To thoroughly understand the scope and hoisting of JS, just remember the following three points:1. All declarations will be promoted to the top of the scope2, the same variable declaration is only made once, and therefore other declarations will be

function is an empty string (P176), which returns the original name of the named function in ES6. 5 } 6 SayHello (); // # Note the following situation1 //don't do that. Because of the reason for the function declaration promotion, the following code is invalid in ECMAScript, and the browser tries to fix the error in an inconsistent manner. P1762 varFlag =true;3 if(flag) {4 functionSayhi () {5Console.log ("Hi");6 }7}Else{8 functionSayhi () {9Console.log ("Yo");Ten } O

,other:undefined,none:null,releasedate:new Date (1),};var J1 = json.stringify (obj); Console.log (J1); var j2 = Json.parse (j1,function (key,value) {if (key = = "ReleaseDate") {return new Date (value);} else {return value;}}); Console.log (J2); Console.log (J2.releaseDate.getFullYear ()); {"name": "Leo", "Age": +, "marry":false, "none":null, "ReleaseDate": "2011-11-30t16:00:00.000z "}falsenull, Releasedate:thu Dec 00:00:00 gmt+0800 (China Standard Time)}age:19marry:falsename: "Leo" None:nullrel

chmod 777 android-skd-linux/-RSyntax: chmod [who] [+ |-| =] [mode] File nameThe meaning of each option in the command isU means "user", which is the owner of the file or directory.G means "same group user", that is, all users who have the same group ID as the file owner.O means "other (others) users".A means "all users". It is the system default value.The operation symbols can be:+ Add a permission.-Cancels a permission.= gives the given permission and cancels all other permissions, if any.Setti

Method One, modify the passwd file1. Edit the passwd filesudo vim/etc/passwd2, find the user you want to mention the right (such as test), the user name after the number changed to 0Find User testtest:x: +::/home/Test Modify Permissions test:x:0:0::/home/test3. Restart the computer and log in to the test account.Method Two, temporarily use the root userSu RootThen enter the root password, if it is the first time to use the root user, will prompt the password error, need to change the root accoun

JavaScript is not a block-scoped scope, and the variable declared in the statement block becomes the local variable of the code fragment where the statement block resides. For example:1 if (true) {2 var x=3; 3 }4 console.log (x);Result Output 3.Again such as:1 var x=5; 2 3 function A () {4 if (! x) {5 var x=10; 6 }7 console.log (x); 8 }9 A ();The result is 10. Because of the promotion of variable declarations, the principle is this, for example:1 if (a==undefined) {2 alert ("OK");

Affected Systems: Microsoft Windows XP SP2 Microsoft Windows XP SP1 Microsoft Windows XP Microsoft Windows Server 2003 SP1 Microsoft Windows Server 2003 Microsoft Windows 2000SP4 Microsoft Windows 2000SP3 Microsoft Windows 2000SP2 Microsoft Windows 2000SP1 Microsoft Windows 2000 Microsoft Windows 　　 Detailed Description: Microsoft Windows is a very popular operating system released by Microsoft. A privilege elevation vulnerability exists in

JS---Pre-parsing, declaring elevation

};The function constructor constructor is in the following form:var Func2 = new Function ("Para1", "Para2",..., "Function body"); What needs to be explained here is that only the function declaration form can be promoted! For example:function declaration Functions MyTest1 () { func (); function func () { Console.log ("I can be promoted"); }} myTest1 ();//Functional expression Functions MyTest2 () { func (); var func = function () { Console.log ("I cannot be

(LABEL_GDT), (char*) LABEL_GDT}; Segment bounds, base address asm Void Main () {MOV ax, CS mov ds, ax mov es, ax//clear screen mov ah, 06h//screen initialization or roll mov al, 00h//ah = 6, Al = 0h mov BX, 1110h//blue background mov cx, 0//upper left corner: (0, 0) mov dl, 4FH//No. 0 column mov dh, 1fh//No. 0 Line int 10h//display interrupt Lgdt GDTPTR//Load GDTR CLI//OFF interrupt//Open Address line A20 in Al, 92h or Al, 00000010b out 92h, AL//ready to switch to protected mode, place CR0 PE b

Title DescriptionThere is a two-dimensional matrix, each row of elements, left to right to maintain a strict increment, the elements of each column, from top to bottom to maintain a strict increment. Finds the given element Elem, returning null or element position. 1 3 7 15 16 2 5 8 17 19 3 6 9 18 20 7 18 20 22 24 9 23 24 28

. Subclasses have the responsibility to extend the superclass, rather than the responsibility of displacing (Override) off or unregistering (nullify) out.4. Inheritance can only be used if it is taxonomic and not inherited from a specific class.The difference between an interface and an abstract class:1. Abstract classes can provide implementations of certain methods. If you add a new, concrete method to an abstract class, all of the subclasses get this method in a single swoop. Interface does n

feeling should be hidden, rather than covering, as for the difference between overloading, covering, hiding, etc., there is time behind to write a blog summary.The volume of a derived class object's memory space-derived class object is equal to the volume of the base class object, plus the volume of the derived class object's own member variable.in a derived class object, contains the base class object, and where the base class object is stored in the new member variable of the derived class ob

is crooked.2, the dichotomy algorithm, the principle remembers, but a long time did not write, wrote the wrong no Grass manuscript paper, I write again big, fork off there is no place to write, very embarrassed. So I wrote the idea on it.3, manually enter a URL (specifically what is forgotten) after, to return to the page, what is the process. (This is roughly the case).4, how to optimize the server response speed?Awkward, no, optimize the database? Increase server Configuration 233 ... The gra

":" Npu "},{" stu_id ": 2," Stu_name ":" Wang Liu "," age ": 0," Birthday ":" Feb 2, 1999 12:00:00 AM " , "Sex": "female", "school": "Xi ' an XI ' an"},{"stu_id": 3, "Stu_name": "66", "age": 0, "Birthday": "Jan 1," 12:00:00 AM "," Sex ":" Female "," School ":" Changan "},{" stu_id ": 4," Stu_name ":" Zhang Yi "," age ": 0," Birthday ":" June, 1994 12:00:00 AM "," Sex ":" female "," school ":" Shaanxi Normal "}, {"stu_id": 5, "Stu_name": "Zhao Liu", "age": 0, "Birthday": "Dec, 12:00:00 AM", "Sex

than the subquery returns, which is greater than the maximum value of the returned result.= all meaningless and logically not tenable.　　　　　　# #多列子查询So far you have been able to complete single-row and multiline subqueries, but only one column is compared in the WHERE or HAVING clause of the SELECT statement.If you want to compare multiple columns, you must write a compound WHERE clause with a logical operator.Dolez queries allow you to combine multiple conditions in a WHERE clause into a single