Assuming, you are posting to grid with id (list1), here is the sample JS code.
"id" is PK (e.g. 123), "oper" will be "edit" for editing record. Rest are the table fields in myData.

<script>
auto_edit = function ()
{
myData = {};
myData.id = "123";
myData.oper = 'edit';
myData.invdate = '2013-06-12';
myData.note = 'test2';
myData.total = '22';
myData.client_id = '10';
jQuery.ajax({
url: "?grid_id=list1",
dataType: "json",
data: myData,
type: "POST",
error: function(res, status) {
alert(res.status+" : "+res.statusText+". Status: "+status);
},
success: function( data ) {
}
});
jQuery("#list1").jqGrid().trigger('reloadGrid',[{page:1}]);
}
</script>

<button onclick="auto_edit()">Edit</button>

refer FAQ query 'How to post data using JS code?' for addition.

100% ok!
Thank you Sir!

Does It work even with subgrid?
I try code in FAQ " How to post data using JS code?".
When I paste It in alternate-row.php (demos), I successfully add new rows, but when I do the same in subgrid_detail.php, I got an error=> 200:OK.Status:parsererror.
Naturally in the last case, I just update two lines of the code:

url: "?grid_id=sub1",
jQuery("#sub1").jqGrid().trigger('reloadGrid',[{page:1}]);

Am I wrong??

Thankyou in advance.

Hello,

The subgrid-detail has different ID format, that is generated based on parent row of grid. It should not necessarily be sub1.
If your subgrid_detail.php page, if your grid object is $g, you can read the subgrid id using: $g->id

So, in your JS code, you can replace sub1 with:
<?php echo $g->id?>

I have replaced sub1 like your suggestion, but still doesn't work. Same parsererror message.
This is my code in subgrid_detail.php:

<script>
auto_add = function ()
{
myData = {};
myData.id = "_empty";
myData.oper = 'add';
myData.invdate = '2013-06-12';
myData.note = 'test2';
myData.total = '22';
myData.client_id = '10';
jQuery.ajax({
url: "?grid_id=<?php echo $g->id?>",
dataType: "json",
data: myData,
type: "POST",
error: function(res, status) {
alert(res.status+" : "+res.statusText+". Status: "+status);
},
success: function( data ) {
}
});
jQuery('#<?php echo $g->id?>').jqGrid().trigger('reloadGrid',[{page:1}]);
}
</script>

I just rechecked it and it need some more changes:

#1)
url: "subgrid_detail.php?grid_id=sub1&subgrid=<?php echo str_replace("_sub1","",$g->id) ?>",

#2)
jQuery('#<?php echo $g->id?>').trigger('reloadGrid',[{page:1}]);

Full JS Code:

<script>
auto_add = function ()
{
myData = {};
myData.id = "_empty";
myData.oper = 'add';
myData.invdate = '2013-06-12';
myData.note = 'test2';
myData.total = '22';
myData.client_id = '10';
jQuery.ajax({
url: "subgrid_detail.php?grid_id=sub1&subgrid=<?php echo str_replace("_sub1","",$g->id) ?>",
dataType: "json",
data: myData,
type: "POST",
error: function(res, status) {
alert(res.status+" : "+res.statusText+". Status: "+status);
},
success: function( data ) {
jQuery('#<?php echo $g->id?>').trigger('reloadGrid',[{page:1}]);
}
});

}
</script>

Well done! Thank You.
I want to upgrade my license to 2.0, How I can do?

Emailed you the links.

Hello,

Another question about grid ID format.
I have a subgrid on a multiple-tab grid.
How I can handle this case?

Thanks.

Please tell the issue you are facing in it. Error screenshot + code would help.
Few things to consider, make sure each grid has unique ID.