javascript - JS function to fill an array with unique elements thorugh generated values -

i'm trying make simple browser game using p5.js. , i've ran problem:

i have array of zombies. zombie object has method getanswer() returns number. i'm trying make function addzombie(), pushes 1 new zombie array. problem don't want repetitive answers in array. current function:

function mkex(){     var values = []     (i=1;i<11;i++){         values.push(i);     }     var signs = ['+','-','/','*'];     var result = -1;     var = 0;     var b = 0;     var c = 0;     var sign1 = "";     var sign2 = "";     while (result<=0){         = values[math.round(math.random()*(values.length-1))];         b = values[math.round(math.random()*(values.length-1))];         c = values[math.round(math.random()*(values.length-1))];         sign1 = signs[math.round(math.random()*(signs.length-1))];         sign2 = signs[math.round(math.random()*(signs.length-1))];         switch(sign1){             case "+":                 switch(sign2){                     case "+":                         result=a+b+c;                         break;                     case "-":                         result=a+b-c;                         break;                     case "/":                         if (b%c==0){                             result=a+b/c;                         }                         break;                     case "*":                         result=a+b*c;                         break;                     default:                         break;                 }                 break;             case "-":                 switch(sign2){                     case "+":                         result=a-b+c;                         break;                     case "-":                         result=a-b-c;                         break;                     case "/":                         if (b%c==0){                             result=a-b/c;                         }                         break;                     case "*":                         result=a-b*c;                         break;                     default:                         break;                 }                 break;             case "/":                 switch(sign2){                     case "+":                         if (a%b==0){                             result=a/b+c;                         }                         break;                     case "-":                         if (a%b==0){                             result=a/b-c;                         }                         break;                     case "/":                         if (a%b==0){                             if (a/b%c==0){                                 result=a/b/c;                             }                         }                         break;                     case "*":                         if (a%b==0){                             result=a/b*c;                         }                         break;                     default:                         break;                 }                 break;             case "*":                 switch(sign2){                     case "+":                         result=a*b+c;                         break;                     case "-":                         result=a*b-c;                         break;                     case "/":                         if (a*b%c==0){                             result=a*b/c;                         }                         break;                     case "*":                         result=a*b*c;                         break;                     default:                         break;                 }             break;             default:                 break;         }     }     var expr = ""+a+sign1+b+sign2+c;     var ret = [expr, result];     return ret; }   function addzombie(){     var expr = mkex();     if (zombies.length==0){         zombies.push(new zombie(player.getxy(),expr));     } else{         (i=0;i<zombies.length;i++){             if (zombies[i].getanswer()==expr[1]){                 addzombie();             }         zombies.push(new zombie(player.getxy(),expr));     } } 

the mkex() function returns array containing string , answer. zombie needs player's coordinates spawn away player.

this function doesn't work, still have zombies same answers. please tell me wrong?

using set keep track of answers make solution simpler , faster (since average search time in set o(1))

let answerset = new set(); let zombies = [];  function addzombie() {   let expr = mkex();   let zombie = new zombie(player.getxy(),expr);    while(answerset.has(zombie.getanswer())) {     zombie = new zombie(player.getxy(),expr);   }    answerset.add(zombie.getanswer());   zombies.push(zombie); }