Get the current user permission level on a list item with ecmascript

To Check current users permissions using Ecmascript\Javascript client object model SharePoint 2010.

function checkifUserHasEditPermissions() {context = new SP.ClientContext.get_current();web = context.get_web();this._currentUser = web.get_currentUser();context.load(this._currentUser);context.load(web,'EffectiveBasePermissions');context.executeQueryAsync(Function.createDelegate(this, this.onSuccessMethod), Function.createDelegate(this, this.onFailureMethod));}function onSuccessMethod(sender, args) {if (web.get_effectiveBasePermissions().has(SP.PermissionKind.editListItems)) {//User Has Edit Permissions}}}