javascript - Find string in array using prototype functions -

i have array:

var str = "rrr"; var arr = ["ddd","rrr","ttt"];

i try check if arr contains str. try this:

  var res = arr .find(str);

but on row above not works idea wrong?

find (added in es2015, aka "es6") expects function predicate. you're looking indexof:

var res = arr.indexof(str);

...which finds things comparing them ===. you'll -1 if it's not found, or index if is.

in comment you've said:

no string exists expect null if exists expect true

...which seems bit odd (i'd think you'd want true or false), give that:

var res = arr.indexof(str) != -1 || null;

...because of javascript's curiously-powerful || operator (that's post on blog).

just completeness find:

but can use find; es5 version (in case you're polyfilling not transpiling):

var res = arr.find(function(entry) { return entry === str; });

or in es2015:

let res = arr.find(entry => entry === str);

res null if not found, str if was. then, have str, so... :-) find more useful when you're searching for, say, object property value.

Tomorrow