使用ajax发送表单数据

as far as we want to send all the form input fields which have name attribute, you can do this for all forms, regardless of the field names:

First Solution

function submitForm(form){
    var url = form.attr("action");
    var formData = {};
    $(form).find("input[name]").each(function (index, node) {
        formData[node.name] = node.value;
    });
    $.post(url, formData).done(function (data) {
        alert(data);
    });
}

Second Solution: in this solution you can create an array of input values:

function submitForm(form){
    var url = form.attr("action");
    var formData = $(form).serializeArray();
    $.post(url, formData).done(function (data) {
        alert(data);
    });
}

$.ajax({
  url: "target.php",
  type: "post",
  data: "fname="+fname+"&lname="+lname,
}).done(function(data) {
  alert(data);
});

can you try this :

function f (){
fname  = $("input[name='fname']").val();
lname  = $("input[name='fname']").val();
att=form.attr("action") ;
$.post(att ,{fname : fname , lname :lname}).done(function(data){
alert(data);
});
return true;
}

In your function form is a DOM object, In order to use attr() you need to convert it to jQuery object.

function f(form, fname, lname) {
    action = $(form).attr("action");
    $.post(att, {fname : fname , lname :lname}).done(function (data) {
        alert(data);
    });
    return true;
}

With .serialize()

function f(form, fname, lname) {
    action = $(form).attr("action");
    $.post(att, $(form).serialize() ).done(function (data) {
        alert(data);
    });
    return true;
}

Additionally, You can use .serialize()

I have written myself a function that converts most of the stuff one may want to send via AJAX to GET of POST query.
Following part of the function might be of interest:

  if(data.tagName!=null&&data.tagName.toUpperCase()=="FORM") {
    //Get all the input elements in form
    var elem = data.elements;
    //Loop through the element array
    for(var i = 0; i < elem.length; i++) {
      //Ignore elements that are not supposed to be sent
      if(elem[i].disabled!=null&&elem[i].disabled!=false||elem[i].type=="button"||elem[i].name==null||(elem[i].type=="checkbox"&&elem[i].checked==false))
        continue; 
      //Add & to any subsequent entries (that means every iteration except the first one) 
      if(data_string.length>0)
        data_string+="&";
      //Get data for selectbox
      if (elem[i].tagName.toUpperCase() == "SELECT")
      {
        data_string += elem[i].name + "=" + encodeURIComponent(elem[i].options[elem[i].selectedIndex].value) ;
      }
      //Get data from checkbox
      else if(elem[i].type=="checkbox")
      {
        data_string += elem[i].name + "="+(elem[i].value==null?"on":elem[i].value);
      }
      //Get data from textfield
      else
      {
        data_string += elem[i].name + (elem[i].value!=""?"=" + encodeURIComponent(elem[i].value):"=");
      }
    }
    return data_string; 
  }

It does not need jQuery since I don't use it. But I'm sure jquery's $.post accepts string as seconf argument.

Here is the whole function, other parts are not commented though. I can't promise there are no bugs in it:

function ajax_create_request_string(data, recursion) {
  var data_string = '';
  //Zpracovani formulare
  if(data.tagName!=null&&data.tagName.toUpperCase()=="FORM") {
    //Get all the input elements in form
    var elem = data.elements;
    //Loop through the element array
    for(var i = 0; i < elem.length; i++) {
      //Ignore elements that are not supposed to be sent
      if(elem[i].disabled!=null&&elem[i].disabled!=false||elem[i].type=="button"||elem[i].name==null||(elem[i].type=="checkbox"&&elem[i].checked==false))
        continue; 
      //Add & to any subsequent entries (that means every iteration except the first one) 
      if(data_string.length>0)
        data_string+="&";
      //Get data for selectbox
      if (elem[i].tagName.toUpperCase() == "SELECT")
      {
        data_string += elem[i].name + "=" + encodeURIComponent(elem[i].options[elem[i].selectedIndex].value) ;
      }
      //Get data from checkbox
      else if(elem[i].type=="checkbox")
      {
        data_string += elem[i].name + "="+(elem[i].value==null?"on":elem[i].value);
      }
      //Get data from textfield
      else
      {
        if(elem[i].className.indexOf("autoempty")!=-1) {
          data_string += elem[i].name+"=";
        }
        else
          data_string += elem[i].name + (elem[i].value!=""?"=" + encodeURIComponent(elem[i].value):"=");
      }
    }
    return data_string; 
  }
  //Loop through array
  if(data instanceof Array) {
    for(var i=0; i<data.length; i++) {
      if(data_string!="")
        data_string+="&";
      data_string+=recursion+"["+i+"]="+data[i];
    }
    return data_string;
  }
  //Loop through object (like foreach)
  for(var i in data) {
    if(data_string!="")
      data_string+="&";
    if(typeof data[i]=="object") {
      if(recursion==null)
        data_string+= ajax_create_request_string(data[i], i);
      else
        data_string+= ajax_create_request_string(data[i], recursion+"["+i+"]");
    }
    else if(recursion==null)
      data_string+=i+"="+data[i];
    else 
      data_string+=recursion+"["+i+"]="+data[i];
  }
  return data_string;
}

you can use serialize method of jquery to get form values. Try like this

<form action="target.php" method="post" >
<input type="text" name="lname" />
<input type="text" name="fname" />
<input type="buttom" name ="send" onclick="return f(this.form) " >
</form>

function f( form ){
    var formData = $(form).serialize();
    att=form.attr("action") ;
    $.post(att, formData).done(function(data){
        alert(data);
    });
    return true;
}

The code you've posted has two problems:

First: <input type="buttom" should be <input type="button".... This probably is just a typo but without button your input will be treated as type="text" as the default input type is text.

Second: In your function f() definition, you are using the form parameter thinking it's already a jQuery object by using form.attr("action"). Then similarly in the $.post method call, you're passing fname and lname which are HTMLInputElements. I believe what you want is form's action url and input element's values.

Try with the following changes:

HTML

<form action="/echo/json/" method="post">
    <input type="text" name="lname" />
    <input type="text" name="fname" />

    <!-- change "buttom" to "button" -->
    <input type="button" name="send" onclick="return f(this.form ,this.form.fname ,this.form.lname) " />
</form>

JavaScript

function f(form, fname, lname) {
    att = form.action; // Use form.action
    $.post(att, {
        fname: fname.value, // Use fname.value
        lname: lname.value // Use lname.value
    }).done(function (data) {
        alert(data);
    });
    return true;
}

Here is the fiddle.