// Suppose jqArr is the array stated above:
var result = [];

angular.forEach(jqArr, function(v_i){
   if(result.length === 0){
      result.push(v_i);
   } else {
      var isPushed = false;
      angular.forEach(result, function(v_j){
         if(angualr.equals(v_i, v_j)){
           isPushed = true;
         }
      });
      if(isPushed === false){
         result.push(v_i);
      }
   }
})
console.log(result);

[e_1, e_2, e_3]

let arr = [1,1,2,2,2,3,4,5,6,6,6,6,6];
let uniq = [...new Set(arr)];

var result = [],
    jqArr = [e_1, e_2, e_3, e_1, e_2];

angular.forEach(jqArr, function(v_i){

// push only the object that aren't inside the result array
   if(result.indexOf(v_i)===-1)
      result.push(v_i);
})
[e_1, e_2, e_3]