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Note4JS.txt
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Note4JS.txt
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1) Js has only Right shift with Zero >>>, but does not have the similar for Left (NO <<<)
2) Js supports Miscellaneous Operator, Ex: result = (a > b) ? 100 : 200;
3) Js have a special Operator is: typeof(var needDetectType);
Note: Undifined return (-->) "undefined", Null --> "object"
4) Js is untyped langquage. As a result, Js provide a special loop called: loop in
for (variablename in object){
statement or block to execute
} --> In each interaction, one property from object will assigned to variablename
and loop continues till all the properties are exhausted.
5) delete is a key word (operator) to delete any property of a particular object
Syntax: delete obj.property OR delete obj['property'] AND will return boolean
Note: Have a lot of note need to aware
Plz read more on: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/delete
6) in Js, there is a term call symbol, read more in: https://developer.mozilla.org/en-US/docs/Glossary/Symbol
7) in Js, there is Loop controll using Loop label
Syntax: 'loopName :(colon)' --> should be in a seperated line of code lonely.
Note: You can use both break and continue for Loop label, Eg: break loopName OR continue loopName
8) in Js, we have a special way to define a function called: function constructor (using Function())
Syntax: var anonymousFunc = Function ('x','y',"alert('Pucca'); return x*y");
OR var literalFunc = function (x, y){alert('Pucca'); return x*y;};//it's a literal function
Note:+ these functions created by that way are called anonymous functions
+ in 2 these ways, key words are different : 1st is Function (4 anonymous), 2nd is function (4 literal)
+ like normal functions,anonymous or literal func can be call by writing their name,Eg:literalFunc(1,2);
+ unlike normal functions, anonymousFuncs can not be access in front of where they are defined
Eg: normal functions: normalFunc(1,2); function normalFunc(x, y) {return x * y;};--> it's ok!!!
anonymous functions: literalFunc(1,2); var literalFunc= function (x, y){return x*y};--> it's an error
9) List of some predefined events are in: https://www.tutorialspoint.com/javascript/javascript_events.htm
10) Js_ document object has cookie not cookies.
11) Js has 2 special functions are: escape(), and unescape()
escape('string') will 'encode' the string --> URI. Eg: 'this is Lam'--> 'this%20is%20Lam'
unescape('string') makes the opposite effect (decode)
Note: have to use escape() to store cookie because cookie do not contain space,' '
12) Plz to read more about cookie in HTML(have 3 good functions):https://www.w3schools.com/js/js_cookies.asp
13) Js has a function will delay another function in n (milisecond)
Syntax: setTimeout('Name of the function',timeDelay)--> the function is a way to call function normally
14) Js has 3 functions: alert, confirm, and prompt
Note-> alert just show message to user, x=confirm('message') //boolean, when user click Cancel, x= false;
x=prompt('message','placeHolder') //when user click OK, x= input of user
//when user click Cancel, x=null
15) in Js, when you want to assign to a variable undefined value, you must use : void(any expression, e.g: 1)--> void(1)
Note: there is not any other way to do this (assign undifined)
16) in Js, there is a special function helping us to print quickly content of the website is: window.print();