A PEG.js parser for ICU MessageFormat strings – part of messageformat.js. Outputs an AST defined by parser.pegjs.
The generated parser function takes two parameters, first the string to be parsed, and a second optional parameter options, an object containing arrays of keywords for cardinal and ordinal rules for the current locale – these are used to validate plural and selectordinal keys. If options or its fields are missing or set to false, the full set of valid Unicode CLDR keys is used: 'zero', 'one', 'two', 'few', 'many', 'other'. To disable this check, pass in an empty array.
npm install messageformat-parser> var parse = require('messageformat-parser').parse; > parse('So {wow}.') [ 'So ', { type: 'argument', arg: 'wow' }, '.' ] > parse('Such { thing }. { count, selectordinal, one {First} two {Second}' + ' few {Third} other {#th} } word.') [ 'Such ', { type: 'argument', arg: 'thing' }, '. ', { type: 'selectordinal', arg: 'count', offset: 0, cases: [ { key: 'one', tokens: [ 'First' ] }, { key: 'two', tokens: [ 'Second' ] }, { key: 'few', tokens: [ 'Third' ] }, { key: 'other', tokens: [ { type: 'octothorpe' }, 'th' ] } ] }, ' word.' ] > parse('Many{type,select,plural{ numbers}selectordinal{ counting}' + 'select{ choices}other{ some {type}}}.') [ 'Many', { type: 'select', arg: 'type', cases: [ { key: 'plural', tokens: [ ' numbers' ] }, { key: 'selectordinal', tokens: [ ' counting' ] }, { key: 'select', tokens: [ ' choices' ] }, { key: 'other', tokens: [ ' some', { type: 'argument', arg: 'type' } ] } ] }, '.' ] > parse('{Such compliance') // SyntaxError: Expected ",", "}" or [ \t\n\r] but "c" found. > var msg = '{words, plural, zero{No words} one{One word} other{# words}}'; > var englishKeys = { cardinal: [ 'one', 'other' ], ordinal: [ 'one', 'two', 'few', 'other' ] }; > parse(msg) [ { type: 'plural', arg: 'words', offset: 0, cases: [ { key: 'zero', tokens: [ 'No words' ] }, { key: 'one', tokens: [ 'One word' ] }, { key: 'other', tokens: [ { type: 'octothorpe' }, ' words' ] } ] } ] > parse(msg, englishKeys) // Error: Invalid key `zero` for argument `words`. Valid plural keys for this // locale are `one`, `other`, and explicit keys like `=0`.