Question

How to get all form value and serialize multiple select with a given variable or an array?
output parameter must be;

id=1&name_1=John&name_2=Juan&name_3=Isabel&name_4=Doe

where the name is in multiple select

Answer 1

As this answer demonstrates, jQuery will use the same ‘name’ value as the key for each selection when serializing via $(form).serialize():

id=1&name=John&name=Juan&name=Isabel&name=Doe

and it’s up the server to understand how to handle it. Chances are that your server will handle it just fine.

If you absolutely require the format you mentioned, you should be able to hack it together using something like this (untested):

var elementArray = $(form).serializeArray();
var modifiedArray = [];
var counts = {};
var multipleValues = {};
$.each(elementArray, function(index, value) {
  if (counts[value.name]){ counts[value.name] += 1; } else { counts[value.name] = 1; }
});
$.each(elementArray, function(index, value) {
  if (multipleValues[value.name] || counts[value.name] > 1){ 
    if (!multipleValues[value.name]) { multipleValues[value.name] = 0; } else { multipleValues[value.name] += 1; }
    modifiedArray.push({name: value.name + "_" + multipleValues[value.name], value: value.value});
  } else {
    modifiedArray.push({name: value.name, value: value.value});
  }
});
var result = $.param(modifiedArray);