javascript - efficiently limiting for...in loop to specific property keys -

i have function loop through nested objects contain precompiled regex patterns. checks each pattern against string, , if matches, replace using "abriv" value.

the code works notice when examining loop in debug mode both 'regex' , 'abriv' property being checked against string.

how optimize loop loop through 'regex' values when conducting second for...in? tried using accessors 'prop.regex' in loop doesnt seem work.

var car = /(\bauto\b|\bvehicle\b|\bride\b)/ig  var bus = /(\bcoach\b)/ig  var train = /(\bexpress\b|\brail\b)/ig    var regexlist = {    car: {      abriv: 'car',      regex: car    },    bus: {      abriv: 'bus',      regex: bus    },    train: {      abriv: 'train',      regex: train    }  }    var teststring = "i drove auto";    function replacer(text) {    (var regex in regexlist) {      var obj = regexlist[regex];      (var prop in obj) {          if (obj.regex.test(text) === true) {          this.text = text.replace(obj.regex, obj.abriv);          return this;        }      }      }  }    replacer(teststring);

i think don't need second loop.

function replacer(text) {   (var regex in regexlist) {     var obj = regexlist[regex];       if (obj.regex.test(text) === true) {         this.text = text.replace(obj.regex, obj.abriv);         return this;       }   } } 

is there missing here ?