javascript - How can I parse a string as an integer and keep decimal places if they are zeros? - Stack Overflow

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I have these strings: "59.50" & "30.00"

What I need to do is convert them to integers but keep the trailing zeros at the end to effectively return:

59.50
30.00

I've tried:

Math.round(59.50 * 1000) / 1000
Math.round(30.00 * 1000) / 1000

but ended up with

59.5
30

I'm assuming I need to use a different method than Math.round as this automatically chops off trailing zeros.

I need to keep these as integers as they need to be multiplied with other integers and keep two decimals points. T thought this would be fairly straight forward but after a lot of searching I can't seem to find a solution to exactly what I need.

Thanks!

I have these strings: "59.50" & "30.00"

What I need to do is convert them to integers but keep the trailing zeros at the end to effectively return:

59.50
30.00

I've tried:

Math.round(59.50 * 1000) / 1000
Math.round(30.00 * 1000) / 1000

but ended up with

59.5
30

I'm assuming I need to use a different method than Math.round as this automatically chops off trailing zeros.

I need to keep these as integers as they need to be multiplied with other integers and keep two decimals points. T thought this would be fairly straight forward but after a lot of searching I can't seem to find a solution to exactly what I need.

Thanks!

• javascript
• math

Share Improve this question Follow asked Mar 10, 2015 at 17:08 LT86LT86 65544 gold badges1515 silver badges2929 bronze badges 5

• If you parse a string as an integer you're chopping off the fractional part by definition. – Pointy Commented Mar 10, 2015 at 17:10
• 59.50 is not an integer – Dancrumb Commented Mar 10, 2015 at 17:10
• Use toFixed(2) when you're displaying the numbers to show 2 decimal places. – Barmar Commented Mar 10, 2015 at 17:12
• Numbers can't have trailing zeros, but you can multiply strings without issue... – dandavis Commented Mar 10, 2015 at 17:12
• These are floats rather than integer but I think you want to make something like that: Math.floor(parseFloat("59.50")).toFixed(2); if you want just 2 leading 0. – briosheje Commented Mar 10, 2015 at 17:12

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5 Answers 5

Sorted by: Reset to default 5

Your premise is flawed. If you parse a number, you are converting it to its numerical representation, which by definition doesn't have trailing zeros.

A further flaw is that you seem to think you can multiply two numbers together and keep the same number of decimal places as the original numbers. That barely makes sense.

It sounds like this might be an XY Problem, and what you really want to do is just have two decimal places in your result.

If so, you can use .toFixed() for this:

var num = parseFloat("59.50");
var num2 = parseFloat("12.33");
var num3 = num * num2

console.log(num3.toFixed(2));  // 733.64

Whenever you want to display the value of the variable, use Number.prototype.toFixed(). This function takes one argument: the number of decimal places to keep. It returns a string, so do it right before viewing the value to the user.

console.log((123.4567).toFixed(2)); // logs "123.46" (rounded)

To keep the decimals - multiply the string by 1 example : "33.01" * 1 // equals to 33.01

Seems you are trying to retain the same floating point, so better solution will be some thing like

parseFloat(string).toFixed(string.split('.')[1].length);

If you want numbers with decimal points, you are not talking about integers (which are whole numbers) but floating point numbers.

In Javascript all numbers are represented as floating point numbers.

You don't need the trailing zeros to do calculations. As long as you've got all the significant digits, you're fine.

If you want to output your result with a given number of decimal values, you can use the toFixed method to transform your number into a formatted string:

var num = 1.5
var output = num.toFixed(2) // '1.50'
// the number is rounded
num = 1.234
output = num.toFixed(2) // '1.23'
num = 1.567
output = num.toFixed(2) // '1.57'

Here's a more detailed description of toFixed: https://developer.mozilla/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toFixed

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