JavaScript data type (top)

There are 6 types of JavaScript data:

1. numeric data type (number);
2. strings (string);
3. Boolean data (Boolean);
4. Objects (object);
5. Null (NULL);
6. Undefined (Undefined).

(a), number

var a = 12;alert (a);

The value of eject a is 12.

var a = 12;         

"typeof is the type of view variable. " the number that pops up is number, the return parameter of a is number, the type is number type" uppercase letter is data type, lowercase letter is the return parameter "

(b), String

var a = ' abc ';        alert (a);

The value of a pop-up is ABC.

var a = ' abc '; alert (typeof a);

The popup is a string, stating that A's return parameter is a string, and the type is of type string.

var a = ' 2 ' + ' 3 ';       alert (a);

The value of a pops up is 23, because at this point 2 and 3 are a string, that is, 2 and 3 are merged together.

var a = ' 2 ' + ' 3 '; Aert (typeof a);

The popup is a string, stating that A's return parameter is a string, and the type is of type string.

var a = ' 2 ' +3;        alert (a);

The value of a that pops up is 23.

var a = ' 2 ' +3; Alert (typeof a);

The return value is string, indicating that a is a string data type at this point.

var a = ' 2 ' +3+4+ ' 5 ';         alert (a);

The popup is also 2345, because it is in order, ' 2 ' +3 is a string, string plus 4 or string, String plus string ' 5 ' is finally a string. therefore for 2345.

var a = ' 2 ' + (3+4) + ' 5 ';         alert (a);

The value of a that pops up is 275.

var a = ' 2 ' + (3+4) + ' 5 '; Alert (typeof a);

The return value that pops up is string and is still a string data type.

var a = ' 2 '-' 1 ';         alert (a);

The value of a that pops up is 1. Because in JS, only the "-" string is subtracted.

var a = ' 2 '-' 1 '; Alert (typeof a);

The return value of the popup is number, which is the numeric value type.

var a = ' 2 '-1;         alert (a);

The value of a that pops up is 1.

var a = ' 2 ' -1;alert (typeof a);

The return value of the popup is number, which is the numeric value type.

(c), Boolean

var a = true;         alert (a);

The value that pops up is true.

var a = True;alert (typeof a);

The value returned is a Boolean. The description data type is a Boolean type.

Not finished ...

JavaScript data type (top)