HTML form input tag name element array with JavaScript

Question

This is a two part question   Someone answered a similar question the other day  which also contained info about this type of array in PHP   but I cannot find it   1   First off  what is the correct terminology for an array created on the end of the name element of an input tag in a form    lt form gt        lt input name  p id    value  0   gt       lt input name  p id    value  1   gt       lt input name  p id    value  2   gt    lt  form gt    2   How do I get the information from that array with JavaScript  Specifically  I am right now just wanting to count the elements of the array   Here is what I did but it isn t working   function form check        for var i   0  i  lt  count document form p id     i        Error on this line          if  document form p name i  value                     window alert  Name Message                document form p name i  focus                break                     else              if  document form p price i  value                         window alert  Price Message                    document form p price i  focus                    break                             else                  update confirmation

User · Answer

document form p id length     not count     You really should give your form an id   lt form id  myform  gt    Then refer to it using   var theForm   document getElementById  myform      Then refer to the elements like   for var i   0  i  lt  theForm p id length  i

User · Answer

Here   s some PHP and JavaScript demonstration code that shows a simple way to create indexed fields on a form  fields that have the same name  and then process them in both JavaScript and PHP  The fields must have both  ID  names and  NAME  names  Javascript uses the ID and PHP uses the NAME      lt  php    How to use same field name multiple times on form    Process these fields in Javascript and PHP    Must use  ID  in Javascript and  NAME  in PHP  echo   lt HTML gt    echo   lt HEAD gt      gt   lt script type  text javascript  gt  function TestForm form       Loop through the HTML form field  TheId  that is returned as an array      The form field has multiple  n  occurrences on the form  each which has the same name     This results in the return of an array of elements indexed from 0 to n-1     Use ID  in Javascript var i   0  document write   lt P gt Javascript responding to your button click  lt  P gt     for  i 0  i  lt  form TheId length  i        document write form TheId i  value     document write   lt br gt            lt  script gt   lt  php echo   lt  HEAD gt    echo   lt BODY gt     DQ           Constant for building string with double quotes in it   if  isset   POST  MyButton          TheNameArray     POST  TheName       Use NAME in PHP   echo   lt P gt Here are the names you submitted to server  lt  P gt      for   i   0   i  lt 3   i             echo  TheNameArray  i      lt BR gt           echo   lt P gt Enter names and submit to server or Javascript lt  P gt    echo   lt FORM NAME TstForm METHOD POST ACTION     echo  DQ    TestArrayFormToJavascript2 php     DQ    OnReset      DQ    return allowreset this      DQ     gt    echo   lt FORM gt    echo   lt INPUT ID   TheId NAME      DQ    TheName       DQ     VALUE      DQ         DQ     gt    echo   lt INPUT ID   TheId NAME      DQ    TheName       DQ     VALUE      DQ         DQ     gt    echo   lt INPUT ID   TheId NAME      DQ    TheName       DQ     VALUE      DQ         DQ     gt    echo   lt P gt  lt INPUT TYPE submit NAME MyButton VALUE      DQ    Submit to server        DQ     gt  lt  P gt    echo   lt P gt  lt BUTTON onclick      DQ    TestForm this form      DQ     gt Submit to Javascript lt  BUTTON gt  lt  P gt     echo   lt  FORM gt    echo   lt  BODY gt    echo   lt  HTML gt

User · Answer

1   First off  what is the correct terminology for an array created on the end of the name element of an input tag in a form     Oftimes Confusing PHPism   As far as JavaScript is concerned a bunch of form controls with the same name are just a bunch of form controls with the same name  and form controls with names that include square brackets are just form controls with names that include square brackets   The PHP naming convention for form controls with the same name is sometimes useful  when you have a number of groups of controls so you can do things like this    lt input name  name 1   gt   lt input name  email 1   gt   lt input name  sex 1   type  radio  value  m  gt   lt input name  sex 1   type  radio  value  f  gt    lt input name  name 2   gt   lt input name  email 2   gt   lt input name  sex 2   type  radio  value  m  gt   lt input name  sex 2   type  radio  value  f  gt      but does confuse some people  Some other languages have adopted the convention since this was originally written  but generally only as an optional feature  For example  via this module for JavaScript       2   How do I get the information from that array with JavaScript     It is still just a matter of getting the property with the same name as the form control from elements  The trick is that since the name of the form controls includes square brackets   you can t use dot notation and have to use square bracket notation just like any other JavaScript property name that includes special characters   Since you have multiple elements with that name  it will be a collection rather then a single control  so you can loop over it with a standard for loop that makes use of its length property   var myForm   document forms id of form  var myControls   myForm elements  p id      for  var i   0  i  lt  myControls length  i          var aControl   myControls i

User · Answer

Try this something like this   var p ids   document forms 0  elements  p id      alert p ids length   for  var i   0  len   p ids length  i  lt  len  i        alert p ids i  value

User · Answer

To answer your questions in order      1  There is no specific name for this   It s simply multiple elements with the same name  and in this case type as well    Name isn t unique  which is why id was invented  it s supposed to be unique     2      function getElementsByTagAndName tag  name          you could pass in the starting element which would make this faster     var elem   document getElementsByTagName tag         var arr   new Array        var i   0      var iarr   0      var att      for   i  lt elem length  i              att   elem i  getAttribute  name            if att    name                arr iarr    elem i               iarr                        return arr

[javascript] HTML form input tag name element array with JavaScript

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