How to change select through $.each, without using any ids? – Jquery

I have a form where I’m using Bootstrap container, rows and cols. In every row can be 1+ cols, and in every col can be one of two:

1. checkbox, label, select:

<input type="checkbox">
<label> Some lable_1 </label>
<select class="select2">
  <option> Something </option>
</select>

or
2) checkbox, label, input:

<input type="checkbox">
<label> Some label_2 </label>
<input type="text" class="form-control">

Also I have a button to clear every select / input which checkbox is True.
None that in every col checkbox is the first elem and select / input – last

Here my button code:
<button type="button" class="btn btn-default" onclick="ClearSelectedElems($('#MyFormId'))" > Clear all checked </button>

Here is my function’s code:

function ClearSelectedElems(form) {
  $.each(form[0]['children'], function(index_row, value_row) {
    var row = form[0]['children'][index_row];
    $.each(row['children'], function(index_col, value_col) {
      var col = row['children'][index_col];
      var first = col['children'][0];
      var prev_last = col['children'][col['children']['length'] - 2];
      var last = col['children'][col['children']['length'] - 1];

      //console.log("first['checked']", first['checked']);
      //console.log("prev_last", prev_last);
      //console.log("prev_last['value']", prev_last['value']);          
      //console.log("last", last);

      if (first['checked']) {
        last['value'] = '777777';
        prev_last['value'] = '777777';
      }
    })
  })
}

About my code:
Function gets a jQuery object as input parametr
First loop goes through all rows;
Second loop goes through all cols in current row;
var first – checkbox of current row and col;
var prev_last – select or some rubish (I will explain lower);
var last – input of current row and col;

`if ()` - if checkbox is checked ---> change select / input field

I use prev_last and last together because when I meet select it isnt last element in current object’children it has this: [0 - ..., 1 - ..., n-1 - select, n - span]

I want to clear all selected elements without id’s through jQuery’s $.each, but I met a problem which I can’t solve.
I hope I has writen my problem quite clear and you will be able to understand the condition and help me.

I have learnt how to get ‘checked’ property from checkboxes,
also I can get and set ‘value’ property from and for inputs,
the only thing I can’t do now is to get / set value for inputs (it throws error when I write prev_last[‘value’] Can you help me please?

I tried only algorithm from above and coundn’t succeed.
Also I tried to do it throug id’s but also failed. (want to mention that ther first idea is better for my look because I can easyly add / remove rows and cols and it will work anyway without any need to rewrite all id’s by programmer’s hands)