Number utils

[blanchco]

Description

1. Created some functions to do some conversions for the new input field:

• number -> exponential
• exponential -> number
• number -> NIST
• NIST -> number
• displaying a number (this depends on the length)

2. I have made the input for all these functions a string, since we can deal with very small or very large numbers it can lead to precision issues if we were to use the Number library to manipulate these inputs

3. UNIT TESTS!!

[mwdchang]

With regards to point-2, I am a bit confused if you are referring to floating-point precision, or if you are talking about allowing arbitrary precision.

• If the former, string vs number will not solve anything, the problem is inherently baked into binary representation. Short of using a specialized library we just need to be careful and deal with it. e.g. 0.2 * 0.2 != 0.04
• if the latter, I don't think we need to worry too much about it. Our problem domains should not have extremely large numbers or exceedingly small numbers.

And to illustrate the number vs string precision problem:

> Number(1000000000000000000000000).toExponential(20)
< '9.99999999999999983223e+23'

So overall it would be good if you elaborate a bit more on the design goals.

[blanchco]

@mwdchang I've address these comments and am focusing on formatting rather than parsing.

Change made:
removed cleanNumberString
removed numberToExponential, we can just use toExponential
exponentialToNumber now uses toLocaleString to properly display the full number rather than the custom parsing
numberToNist is relatively unchanged aside from using parseFloat to clean the number input
nistToNumber cleans all whitespaces and then parseFloat rather than the custom parsing

[liunelson]

Need example here and nistToNumber and displayNumber for this rule

However, when there are only four digits before or after the decimal marker, we recommend that no space is required and no space should be used

For example:
1234.123 -> 1234.123
1234.1234 -> 1234.1234
11234.123 -> 11 234.123
1234.12344 -> 1 234.123 44
11234.123 -> 11 234.123
11234.1234 -> 11 234.123 4

[liunelson]

Probably should handle this number with thin spaces and exponentials
e.g. -1 234.567 89e+1 -> -1.234 567 89e+4 -> -12345.6789