I18n WP Plugin
============
Originally from i18n-calypso, but here moment.js is stripped due to build size.

This lib enables translations, exposing three public methods:

* .translate()
* .numberFormat()

It also provides a Higher-Order Component named localize(). Wrapping your component in localize() will give it the aforementioned functions as props. This is the suggested way of using them with React components.

Finally, this lib exposes a utility method for your React application:

* .hasTranslation()

Translate Method

translate() accepts up to three arguments (string, string, object), depending on the translation needs. The second and/or third parameter can be omitted:

``
/**
* @param {string} original - the string to translate, will be used as single version if plural passed
* @param {string} [plural] - the plural string to translate (if applicable)
* @param {object} [options] - properties describing translation requirements for given text
**/
`

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The following attributes can be set in the options object to alter the translation type. The attributes can be combined as needed for a particular case.

* options.args [string, array, or object] arguments you would pass into sprintf to be run against the text for string substitution. See docs
* options.components [object] markup must be added as React components and not with string substitution. See mixing strings and markup.
* options.comment [string] comment that will be shown to the translator for anything that may need to be explained about the translation.
* options.context [string] provides the ability for the translator to provide a different translation for the same text in two locations (_dependent on context_). Usually context should only be used after a string has been discovered to require different translations. If you want to provide help on how to translate (which is highly appreciated!), please use a comment.

Usage

If you pass a single string into translate, it will trigger a simple translation without any context, pluralization, sprintf arguments, or comments. You would call it like this.

`js
var i18n = require( 'i18n-wp-plugin' );
var translation = i18n.translate( 'Some content to translate' );
`

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Translation strings are extracted from our codebase through a process of static analysis and imported into GlotPress where they are translated (more on that process here). So you must avoid passing a variable, ternary expression, function call, or other form of logic in place of a string value to the translate method. The _one_ exception is that you can split a long string into mulitple substrings concatenated with the + operator.

`js
/----------------- Bad Examples -----------------/

// don't pass a logical expression argument
var translation = i18n.translate( condition ? 'foo' : 'bar' );

// don't pass a variable argument
var translation = i18n.translate( foo );

// don't pass a function call argument
var translation = i18n.translate( foo( 'bar' ) );

/----------------- Good Examples -----------------/

// do pass a string argument
var example = i18n.translate( 'foo' );

// do concatenate long strings with the + operator
var translation = i18n.translate(
'I am the very model of a modern Major-General, ' +
'I\'ve information vegetable, animal, and mineral, ' +
'I know the kings of England, and I quote the fights historical ' +
'from Marathon to Waterloo, in order categorical.'
);
`

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The translate() method uses sprintf interpolation for string substitution (see docs for syntax details). The option.args value is used to inject variable content into the string.

`js
// named arguments (preferred approach)
i18n.translate( 'My %(thing)s has %(number)d corners', {
args: {
thing: 'hat',
number: 3
}
} );
// 'My hat has 3 corners'

// argument array
i18n.translate( 'My %s has %d corners', {
args: [ 'hat', 3 ]
} );
// 'My hat has 3 corners'

// single substitution
i18n.translate( 'My %s has 3 corners', {
args: 'hat'
} );
// 'My hat has 3 corners'
`

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Because React tracks DOM nodes in the virtual DOM for rendering purposes, you cannot use string substitution with html markup as you might in a php scenario, because we don't render arbitrary html into the page, we are creating a virtual DOM in React.

Instead we use the interpolate-components module to inject components into the string using a component token as a placeholder in the string and a components object, similar to how string substitution works. The result of the translate() method can then be inserted as a child into another React component. Component tokens are strings (containing letters, numbers, or underscores only) wrapped inside double-curly braces and have an opening, closing, and self-closing syntax, similar to html.

NOTE: Always use a JSX element for passing components. Otherwise you will need to wrap your React classes with createFactory. Any wrapped content inside opening/closing component tokens will be inserted/replaced as the children of that component in the output. Component tokens must be unique:

`js
// self-closing component syntax
var example = i18n.translate( 'My hat has {{hatInput/}} corners', {
components: {
hatInput:
}
} );

// component that wraps part of the string
var example2 = i18n.translate( 'I feel {{em}}very{{/em}} strongly about this.', {
components: {
em:
}
} );

// components can nest
var example3 = i18n.translate( '{{a}}{{icon/}}click {{em}}here{{/em}}{{/a}} to see examples.', {
components: {
a: ,
em: ,
icon:
}
} );


`

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You must specify both the singular and plural variants of a string when it contains plurals. If the string uses placeholders that will be replaced with actual values, then both the plural and singular strings should include those placeholders. It might seem redundant, but it is necessary for languages where a singular version may be used for counts other than 1.


`js

// An example where the translated string does not have
// a number represented directly, but still depends on it
var numHats = howManyHats(), // returns integer
content = i18n.translate(
'My hat has three corners.',
'My hats have three corners.',
{
count: numHats
}
);

// An example where the translated string includes the actual number it depends on
var numDays = daysUntilExpiration(), // returns integer
content = i18n.translate(
'Your subscription will expire in %(numberOfDays)d day.',
'Your subscription will expire in %(numberOfDays)d days.',
{
count: numDays,
args: {
numberOfDays: numDays
}
}
);

`

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`js
// simplest case... just a translation, no special options
var content = i18n.translate( 'My hat has three corners.' );

// sprintf-style string substitution
var city = getCity(), // returns string
zip = getZip(), // returns string
content = i18n.translate( 'Your city is %(city)s, your zip is %(zip)s.', {
args: {
city: city,
zip: zip
}
} );

// Mixing strings and markup
// NOTE: This will return a React component, not a string
var component = i18n.translate( 'I bought my hat in {{country/}}.', {
components: {
country:
}
} );

// Mixing strings with markup that has nested content
var component = i18n.translate( 'My hat has {{link}}three{{/link}} corners', {
components: {
link:
}
} );

// add a comment to the translator
var content = i18n.translate( 'g:i:s a', {
comment: 'draft saved date format, see http://php.net/date'
} );

// providing context
var content = i18n.translate( 'post', {
context: 'verb'
} );

`

See the test cases for more example usage.

numberFormat Method

The numberFormat method is also available to format numbers using the loaded locale settings (i.e., locale-specific thousands and decimal separators). You pass in the number (integer or float) and (optionally) the number of decimal places you want (or an options object), and a string is returned with the proper formatting for the currently-loaded locale. You can also override the locale settings for a particular number if necessary by expanding the second argument into an object with the attributes you want to override.

$3

`js
// These examples assume a 'de' (German) locale to demonstrate
// locale-formatted numbers
i18n.numberFormat( 2500.25 ); // '2.500'
i18n.numberFormat( 2500.1, 2 ); // '2.500,10'
i18n.numberFormat( 2500.33, { decimals: 3, thousandsSep: '', decPoint: '@'} ); // '2500@330'
`

hasTranslation Method

Using the method hasTranslation you can check whether a translation for a given string exists. As the translate() function will always return screen text that can be displayed (will supply the source text if no translation exists), it is unsuitable to determine whether text is translated. Other factors are optional key hashing as well as purposeful translation to the source text.

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