How do I find an array item with TypeScript a modern easier way

Question

Is there a canonical way to find an item in an array with TypeScript  ES6  allows this simple clean approach    quot id quot  1     quot id quot  -2     quot id quot  3   find myObj   gt  myObj id  lt  0      returns   quot id quot  -2   TypeScript implements many ES6  features and continues to do so  It seems likely it has at least as nice a solution  so  How can an item be found in a array using TypeScript  considering ease of use  modern best practices  and elegance via simplicity   restating the question slightly to seek best approaches  Notes   quot item quot  could be a JavaScript object  or almost anything else   The example above happens to be to find plain ol  native JS objects  but many scenarios exist    quot canonical quot  is just a fancy way in Computer Science  and other fields  to say  quot general accepted rule or standard formula quot   remember everyone here didn t know that at some point   This is not about new features  Any version of JS could do this  However the form to do so gets less and less appealing the farther you go back in time   TypeScript roadmap for reference

User · Answer

You could just use underscore library   Install it      npm install underscore --save    npm install  types underscore --save-dev   Import it     import     require  underscore      Use it      var x     filter            id   1       id   -2       id   3           myObj   gt  myObj id  lt  0

User · Answer

Part One - Polyfill  For browsers that haven t implemented it  a polyfill for array find  Courtesy of MDN   if   Array prototype find      Array prototype find   function predicate        if  this    null          throw new TypeError  Array prototype find called on null or undefined              if  typeof predicate      function           throw new TypeError  predicate must be a function              var list   Object this       var length   list length  gt  gt  gt  0      var thisArg   arguments 1       var value       for  var i   0  i  lt  length  i            value   list i         if  predicate call thisArg  value  i  list             return value                    return undefined           Part Two - Interface  You need to extend the open Array interface to include the find method   interface Array lt T gt        find predicate   search  T    gt  boolean    T      When this arrives in TypeScript  you ll get a warning from the compiler that will remind you to delete this   Part Three - Use it  The variable x will have the expected type      id  number    var x       id   1       id   -2       id   3    find myObj   gt  myObj id  lt  0

User · Answer

If you need some es6 improvements not supported by Typescript  you can target es6 in your tsconfig and use Babel to convert your files in es5

User · Answer

Playing with the tsconfig json You can also targeting es5 like this           compilerOptions              experimentalDecorators   true           module    commonjs             target    es5

User · Answer

For some projects it s easier to set your target to es6 in your tsconfig json        compilerOptions          target    es6

[typescript] How do I find an array item with TypeScript? (a modern, easier way)

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