I haven't look into i18n-js library in details, but this is what I can spot so far:
* the message format in i18n-js seems to be compatible with ICU message syntax, the industry standard used in other programming languages and the one used by formatJS as well. we will have to check if they really implemented all the specs, which makes the messages more advanced, e.g.:
```
Cart: {itemCount, plural,
=0 {no items}
one {one item}
other {# items}
}
```
including the fact that itemCount from `other` option will be formatted as a number, saying "1,030" in EN, vs "1 030" in FR.
* i18n-js is a js library, which means you have to do the formatting in your js code, then passing the formatted data into the template engine where you have the placeholders for them, while FormatJS focuses more on the high-level declarative form that you can use in your templates directly, which makes things simpler, if you use handlebars, you could do: {{formatMessage "Cart" itemCount=numItems}} right in your template.
> i18n-js is a js library, which means you have to do the formatting in your js code, then passing the formatted data into the template engine where you have the placeholders for them
I have nothing against Coffeescript, and use it myself sometimes. But please don't respond to something about "js" and then put down a single coffeescript snippet with no additional context. It's very confusing.
I had to re-read the last line several times before I looked up at the function arrow and realized it was coffeescript, and that the "@" were not part of the i18n library, but rather the syntactic sugar for "this".
* the message format in i18n-js seems to be compatible with ICU message syntax, the industry standard used in other programming languages and the one used by formatJS as well. we will have to check if they really implemented all the specs, which makes the messages more advanced, e.g.:
``` Cart: {itemCount, plural, =0 {no items} one {one item} other {# items} } ```
including the fact that itemCount from `other` option will be formatted as a number, saying "1,030" in EN, vs "1 030" in FR.
* i18n-js is a js library, which means you have to do the formatting in your js code, then passing the formatted data into the template engine where you have the placeholders for them, while FormatJS focuses more on the high-level declarative form that you can use in your templates directly, which makes things simpler, if you use handlebars, you could do: {{formatMessage "Cart" itemCount=numItems}} right in your template.