Manually convert types to numeric types JS provides three methods:
Number(object);
parseInt(string, radix);
parseFloat(string, radix).
The specific usage of the three methods is shown in the following table:
Number(object)
| method | example | return value | illustrate |
|---|---|---|---|
| Number() | Number(false) | 0 | If boolean, true and false are converted to 1 and 0 respectively |
| Number(3) | 3 | If it is a numeric value, return itself. | |
| Number(new Date()) | 3 | Returns the number of milliseconds since January 1, 1970. . | |
| Number(null) | 0 | If null, return 0. | |
| Number(undefined) | NaN | If undefined, return NaN. | |
| Number("123") | 123 | If the string contains only numbers, convert it to decimal (ignoring leading 0s) | |
| Number("000.123") | 0.123 | If the string contains a valid floating point format, convert it to a floating point value (ignoring leading zeros) | |
| Number("") | 0 | If it is an empty string, convert it to 0 | |
| Number("Hello word") | NaN | If the string contains a format other than the above, convert it to NaN |
parseInt(string, radix)
| method | example | return value | illustrate |
|---|---|---|---|
| parseInt(string, radix): If the radix parameter is specified, radix is used as the base for parsing |
parseInt(" Acura666") | NaN | Returns NaN if the first character is not a number sign |
| parseInt("666Acura") | 666 | If the first character is a number, continue parsing until the string is parsed or a non-numeric character is encountered | |
| parseInt("22.6sss") | 22 | Convert to an integer, directly remove the decimal point and keep the integer | |
| parseInt("11",2) | 3 | radix is optional. Indicates the radix of the number to parse. The value is between 2 and 36. If this parameter is omitted or its value is 0, the number will be parsed on a 10-base basis. If it starts with "0x" or "0X", it will be base 16. If the argument is less than 2 or greater than 36, parseInt() will return NaN |
parseFloat(string, radix)
| method | example | return value | illustrate |
|---|---|---|---|
| parseFloat(string, radix) rules are basically the same as parseInt |
parseFloat("0.0.000666Acura") | 0 | The first decimal point symbol is valid, parseFloat ignores all leading zeros |
| parseFloat("0.000666") | 0.000666 | ||
| parseFloat("0.2.000666") | 0.2 |
I believe that you can clearly understand these three methods through the above three tables~~