JS data type implicit conversion notes and JS wrapper objects

"37" +7//377

"37"-7//30

Skillfully use +/-rules to change the string x+ ' variable number x-0

JS inside the = = is not strictly equal to

"123" = = 123

0 = = False

Nul l== undefined

New Object () = = new Object ()

[1,2]==[1,2]

But [1,2]===[1,2] is wrong because the reference to the object is compared

Ps:nan values are not equal to anything, even if they are not strictly equal to

———————————————————————————— a==b ————————————————————————————————

If the type is the same, same as = = =

Type not at the same time

Number==string string to number before comparing

boolean==? Boolean Go first number

Object==string|number attempt to convert object to base type other then False

JS Wrapper Object

var str= "123"; alert (str.length); The result is 3 (obviously the string type is not an object, why can I call the Length property?) ）

str.t=3;

alert (STR.T); The result is undefined (why can't it be 3 here)

Explanation: By Mu class bosn teacher

JS data type implicit conversion notes and JS wrapper objects