Pass value of JavaScript variable to Rails view with hidden_field_tag helper

Question

I set up a JavaScript program using jQuery to change the user input values at various form field.

$(document).ready(function(){
    $("#billAmt").keyup(function(){
        var a = $("#billAmt").val();
        var b = a*3/100;
        var d = "<%= current_user.balance %>";
        var c = d - b;
        $("#cashBack").val(b);
        $("#total").val(c);
    });
});

This JavaScript code is inside the form_tag and I would like to pass #cashBack to hidden field.

I did like:

<%= hidden_field_tag :cashBack, nil, :id => "cashBack", :value => ''%>

When I submit the form, params[:cashBack] is empty. So, how do I pass the value and change every time I change the value.

I pass a value in text field with id billAmt. Lets say I enter 100 and user balance is 200 then a = 100, b=3, c = 197 — Santosh Aryal
– Santosh Aryal, Commented Apr 29, 2016 at 1:53

GilmoreGarland · Accepted Answer · 2016-04-29 02:43:21Z

5

In order to set hidden textfield, You must use pure javascript instead of JQuery.

$("#cashBack").get(0).value = b;

answered Apr 29, 2016 at 2:43

GilmoreGarland

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1 Comment

Boomerange Over a year ago

This is the so far the best answer for how to pass variable from javascript to hidden_field/rails erb. Simple and it works like a charm. Thank you ;) Can you describe why we cannot use jQuery and what method get do?

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