javascript - Is it possible to check the condition of a value of an object and JUST return the key? -

i have object of letters , numbers inside of function. function takes in array of numbers , i'm running in loop iterates on object , checks condition. if of numbers in array match of values in object, return just key value.

so if pass in switcher(['26']), should return 'a'. possible?

function switcher(x){ const letters = {   a: '26',   b: '25',   c: '24',   d: '23',   e: '22',   f: '21',   g: '20',   h: '19',   i: '18',   j: '17',   k: '16',   l: '15',   m: '14',   n: '13',   o: '12',   p: '11',   q: '10',   r: '9',   s: '8',   t: '7',   u: '6',   v: '5',   w: '4',   x: '3',   y: '2',   z: '1' }; } 

i have attempted via es6 map() method, unsure put in if statement.. here have far:

return x.map(function(number){   let keys = object.keys(letters);   for(var key in letters){     if(letters[key] === number){     }   }  }); } 

is there easier way this?

you use object.keys , array#find key of matched value.

const letters = {a:'26',b:'25',c:'24',d:'23',e:'22',f:'21',g:'20',h:'19',i:'18',j:'17',k:'16',l:'15',m:'14',n:'13',o:'12',p:'11',q:'10',r:'9',s:'8',t:'7',u:'6',v:'5',w:'4',x:'3',y:'2',z:'1'};    function switcher(num){    var res = object.keys(letters).find(v => letters[v] == num);    return res;  }    console.log(switcher('26'));  console.log(switcher('9'));