Compact and Scientific Notation Syntax

[sffc]

This thread is about the syntax for compact notation and scientific notation.

Compact notation uses localized suffixes like "K" and "M" to represent the magnitude. Scientific notation uses an exponential separator, like "E", followed by a power of ten.

Older versions of ICU exposed each of these as separate "styles" of DecimalFormat. However, newer ICU lets you combine scientific or compact notation with all other number formatting features.

I suggest the following basic syntax:

{ notation: "scientific" }  // 1.2E3
{ notation: "compact-short" }  // 1.2K
{ notation: "compact-long" }  // 1.2 thousand

In addition, we might want to expose additional options for scientific notation. ICU supports three options:

• Engineering notation (exponent is always a multiple of 3)
• Minimum exponent digits: "1.2E03"
• Exponent sign display: "1.2E+3"

If we want to bring these additional options into Ecma 402, we could do something like,

{ notation: "engineering" }
{ notation: "scientific", minimumExponentDigits: 3 }
{ notation: "scientific", exponentSign: "always" }

References:

• NumberFormat: new style scientific ecma402#164
• [Proposal] Compact Decimal Format to abbreviate large numbers ecma402#37

Comments?

[littledan]

LGTM

[littledan]

We discussed this question in the May 2018 Intl meeting. The conclusion was to split this into two options:

• notation: "engineering"/"scientific"/"compact"
• display: "short"/"narrow"/"long"
• Leave further options like minimumExponentDigits and exponentSign for future extensions