Javascript：将字符串转换为整数然后再转换回字符串的最有效方法

Question

I have a text input field which has a value of text to take in a string like "$2,000." In my functionality, I need to convert this back to aa number to run some mathematical functions and then spit it out back as another dollar value, which will be formatted like "$2,500.56" (IE not "$2,500.567"). Here's the two tests I've run so far:

var amount = "$2,000.58"
// "2000.58"
var amount_no_sym = amount.replace(/[^\d\.]/g, '');
//2000.58
var amount_integer = parseFloat(amount_no_sym);
//2000.58 (will cut out any additional decimal places)
var amount_decimals = amount_integer.toFixed(2);
//Final output is "$2,000.58" - the toLocaleString doesn't add back the , here?
var amount_dollar_string = "$" + amount_decimals.toLocaleString();


var amount = "$2,000.58"
// "2000.58"
var amount_no_sym = amount.replace(/[^\d\.]/g, '');
// 2000.58
var amount_integer = parseFloat(amount_no_sym);
//Final output is "$2,000.58"- but sometimes it will be something like "$3,564.345" for certain calculations.
var amount_dollar_string = "$" + amount_integer.toLocaleString();

Would the most optimal solution be to go to the second one, and then write a function to process a string and cut off the last number after the decimal if there are more than two....? Is there a simpler way and I'm doing too much work?

Thanks in advance!

Answer 1

Don't do your own number formatting. There's an API for that.

 var formatter = new Intl.NumberFormat("en-us", { style: "currency", currency: "USD" }); console.log(formatter.format(2000.58)); 

Answer 2

In both cases you can avoid calling the function parseFloat() by using Unary + (plus) operator which attempts to convert the operand to a number, if it is not already. And to format currency you can also use Number.prototype.toLocaleString() passing as arguments the desired locale and an object with options:

 var amount = '$2,000,344.58', amount_integer = +amount.replace(/[^\\d\\.]/g, ''), amount_dollar_string = amount_integer.toLocaleString('en-EN', { style: 'currency', currency: 'USD' }); console.log(amount_integer); console.log(amount_dollar_string);