JS basics - forced type conversion (error-prone, self-use)

1. Convert null and undefined to strings:

① Use the toString function: null and undefined have no tostring() method, and report an error directly

② Use String functions: 'null', 'undefined'

2. Convert other types to Number:

Use the Number function:

① number string --> number

② number + non-numeric string --> NAN

③ empty string --> 0

④ null --> 0

⑤ undefined --> NAN

⑥ true --> 1

⑦ false --> 0

Use the parseInt / parseFloat functions (specifically to convert strings):

① String --> Read the part of numbers from left to right, and stop when the part that is not a number is encountered.

② Non-string --> Convert it to a string and then operate:

• true -->NAN

Tips: parseInt has two parameters, the first parameter is the number to be converted, and the second parameter is the base to be converted.

3, base:

Starting with 0x: hexadecimal

• 0x16

Starting with 0: hexadecimal

• 070

Starting with 0b: binary

• 0b10

4. Convert other types to Boolean:

Use Boolean functions:

① Numbers: Except 0 and NAN are false, the rest are true

② String: Except the empty string is false, the rest are true

③ null: false

④ undefined: false

⑤ Object: true