Summary of data type conversions in JavaScript

Summary of data type conversions in JavaScript

In JS, data type conversions are divided into explicit data type conversions and implicit data type conversions.

1, explicit data-type conversions

A: Turn numbers:

1) Number conversion:

Code:

var a = "123";

A = number (a);

Attention:

A) If the converted content itself is a string of numeric type, it will return itself in the future at the time of conversion.

b) If the converted content itself is not a string of numeric type, then the result is Nan at the time of conversion.

c) If the content to be converted is an empty string, that with the result of the conversion is 0.

D) If it is a different character, the result will be nan at the time of conversion.

2) parseint ():

Code:

var a = "123"; A = parseint (a);

A) ignore the whitespace in front of the string until the first non-null character is found, and the non-numeric string followed by the number is removed.

b) If the first character is not a number sign or minus sign, return Nan

c) The decimal is rounded. (Rounded down)

3) parsefloat ();//floating-point number (decimal)

As with parseint, the only difference is that parsefloat can keep decimals.

B. Transfer string

Other data types can be converted to strings.

1) String ():

Code:

var a = 123;

A = String (a);

2). ToString () method to convert (wrapper class).

Code:

var a = 123; A = A.tostring ();

Undefined,null cannot use ToString.

C. Go to the Boolean type:

Other types can be converted to a Boolean value:

Boolean ():

Code:

var a = "true"; A = Boolean (a);

Note: All content is true after conversion for a Boolean conversion except: false, "" (empty string), 0, NaN, undefined

2, implicit conversion

A) Turn number:

var a = "123";

A = +a;

Subtraction and the remainder of the string can be implicitly converted to number.

b) Turn string:

var a = 123;

A = a + "";

c) Turn to Boolean:

var a = 123;

A =!! A

Summary of data type conversions in JavaScript