How to update Values in Sharepoint list using ajax

Question

I have a html form where using ajax i want to insert the value of that forms fields in SharePoint list

Answer 1

function CreateListItemWithDetails(listName, webUrl, newItemTitle, success, failure) {
    var itemType = GetItemTypeForListName(listName);
    var item = {
        "__metadata": { "type": itemType },
        "Title": newItemTitle
    };

    $.ajax({
        url: _spPageContextInfo.siteAbsoluteUrl + "/_api/web/lists/getbytitle('" + listName + "')/items",
        type: "POST",
        contentType: "application/json;odata=verbose",
        data: JSON.stringify(item),
        headers: {
            "Accept": "application/json;odata=verbose",
            "X-RequestDigest": $("#__REQUESTDIGEST").val()
        },
        success: function (data) {
            success(data);
        },
        error: function (data) {
            failure(data);
        }
    });
}

// Get List Item Type metadata
function GetItemTypeForListName(name) {
    return "SP.Data." + name.charAt(0).toUpperCase() + name.split(" ").join("").slice(1) + "ListItem";
}

Ref :Adding new list item using REST