JavaScript data type and operator __java

1. Original type (6 kinds): Number,string,boolean,null,undefined,object (Function,array,date)

2. Implicit conversion: "37"-7//30

"37" +7//377

Note the use of-+-rule conversion type:

(1) num-0: Converts num type to number;

(2) num+ "": Converts the NUM type to a string;

2. = = operator

"1.23" = 1.23: Strings and numbers are compared, the strings are converted to numbers and then compared;

0 = false;

Null = = undefined;

New Object () = new Object ();

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

3. = = = Strictly equal To

A = = = B:

Returns False if the type is different;

The same type: (1) NULL = = NULL;

(2) undefined = = undefined;

(3) Nan!= nan; (Neither Nan nor any number is equal);

(4) New Object ()!= new Object ();

4.a==b

same type, same = = =

Type is different, try type conversions and comparisons:

(1) NULL = = undefined equal;

(2) Number = = String: Converts a string to number, 1== "1.0"//true;

(3) Boolean = =? : Converts Boolean to number, true to 1,false conversion to 0, and then comparison;

(4) Object = = Number|string: Attempt to convert object to base type, new string ("hi") = = "HI"

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