how to detect all checkbox inputs as being checked

I am trying to basically to a batch operation for any checkbox input. Following code does not work. Thank you for any help.

				{ 
					view:"richselect", width:170, id:"batchAction", labelWidth:90,
					labelAlign:"left",
					value:1, options:[
						{ id:1, value:"action1"   }, 
						{ id:2, value:"action2"   }, 
						{ id:3, value:"action3"   }, 
						{ id:4, value:"action4" }
					],
					on:{
						onchange:function(){
							var str;
							var inputs = $("#batchAction input[type='checkbox']:checked");
							for (var j=0;j < inputs.length; j++) {
								if(inputs.item(j) == "checkbox" && inputs.item(j).checked) {
									str += inputs.item(j).value + ' ';
								}
							}
							console.log(str);
							console.log(inputs);
						}
					}

				},

Even with the following correction:
$("#checkbox input[type=‘checkbox’]:checked");

inputs is unable to access properties of the checked or not? What to do?

Above code use direct DOM manipulation instead of Webix API
You can get all views in the form or only necessary ones by their IDs and use view.setValue to set state of checkbox.