javascript convert string to number or float

javascript variable 轉成 integer:

let float = parseInt(string, 10);

javascript variable 轉成 float:

let float = parseFloat(string);

javascript variable 轉成 numeber:

let float = new Number(string);

除此之外, 還有2個神奇的操作:
https://stackoverflow.com/questions/33544827/convert-string-to-either-integer-or-float-in-javascript

Multiply string which has number data with 1. You will get the Numeric data value.

var int_value = "string" * 1;

In your case

a = '2' * 1; // => parse to integer
b = '2.1' * 1; // => parse to float
c = '2.0' * 1; // => parse to float
d = 'text' * 1; // => don't parse    //NaN value

For last one you will get NaN value. Manually handle for NaN value.

以及使用 eval():
https://www.tutorialspoint.com/how-to-convert-string-into-float-in-javascript

      let string = "3.456"; 
      let float = eval(string);