Oh I got it using following code:
var temp = 85;
var hum = 10;
var HI = -42.379 + 2.04901523temp + 10.14333127hum - .22475541temphum - .00683783temptemp - .05481717humhum + .00122874temptemphum + .00085282temphumhum - .00000199temptemphumhum;
Thanks to this guy @sisball8 . I got it from Heat Index Function for Java Script