数字中的前导和尾随零

Question

I am working on a project where I require to format incoming numbers in the following way:

###.###

However I noticed some results I didn't expect. The following works in the sense that I don't get an error:

 console.log(07); // or in my case: console.log(007); 

Of course, it will not retain the '00' in the value itself, since that value is effectively 7.

The same goes for the following:

 console.log(7.0); // or in my case: console.log(7.000); 

JavaScript understands what I am doing, but in the end the actual value will be 7, which can be proven with the following:

  const leadingValue = 007; const trailingValue = 7.00; console.log(leadingValue, trailingValue); // both are exactly 7 

But what I find curious is the following: the moment I combine these two I get a syntax error:

// but not this:
console.log(007.000);

1) Can someone explain why this isn't working?

I'm trying to find a solution to store numbers/floats with the exact precision without using string.

2) Is there any way in JS/NodeJS or even TypeScript to do this without using strings?

What I currently want to do is to receive the input, scan for the format and store that as a separate property and then parse the incoming value since parseInt('007.000') does work. And when the user wants to get this value return it back to the user... in a string.. unfortunately.

Answer 1

1) 007.000 is a syntax error because 007 is an octal integer literal , to which you're then appending a floating point part. (Try console.log(010) . This prints 8.)

2) Here's how you can achieve your formatting using Intl.NumberFormat ...

 var myformat = new Intl.NumberFormat('en-US', { minimumIntegerDigits: 3, minimumFractionDigits: 3 }); console.log(myformat.format(7)); // prints 007.000 

Answer 2

Hi

You can use an aproach that uses string funtions .split .padStart and .padEnd

Search on MDN

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/split https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/padStart https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/padEnd

Here you have an example:

 const x = 12.1; function formatNumber( unformatedNumber) { const desiredDecimalPad = 3; const desiredNonDecimalPad = 3; const unformatedNumberString = unformatedNumber.toString(); const unformatedNumberArr = unformatedNumberString.split('.'); const decimalStartPadded = unformatedNumberArr[0].padStart(desiredDecimalPad, '0'); const nonDecimalEndPadded = unformatedNumberArr[1].padEnd(desiredNonDecimalPad, '0'); const formatedNumberString = decimalStartPadded + '.' + nonDecimalEndPadded; return formatedNumberString; } console.log(formatNumber(x))