var instance = new Vintasoft.Twain.WebTwainDeviceJS(deviceName, productFamily, manufacturer, driverVersion, twainVersion, deviceManager, is64Bit);

var value; // Type: any

// Parameters
var showUI; // Type: boolean
var showIndicators; // Type: boolean
var successFunc; // Type: function
var errorFunc; // Type: function

value = instance.openAsync(showUI, showIndicators, successFunc, errorFunc);

function openAsync(
   showUI
True - device UI must be shown; false - device UI must NOT be shown.
 : boolean, 
   showIndicators
True - device should show progress indicator during image scan process; false - device should not show progress indicator during image scan process. Default value is true.
 : boolean, 
   successFunc
A function that will be executed if request is executed successfully.
 Function prototype: "successFunc(twainDevice)", where 'twainDevice' parameter is an instance of WebTwainDeviceJS class.
 : Function, 
   errorFunc
A function that will be executed if request is failed.
 Function prototype: "errorFunc(twainDevice, errorMessage)", where 'twainDevice' parameter is an instance of WebTwainDeviceJS class, 'errorMessage' parameter is string that describes error.
 : Function
) : any;

Parameters

showUI

True - device UI must be shown; false - device UI must NOT be shown.

showIndicators

True - device should show progress indicator during image scan process; false - device should not show progress indicator during image scan process. Default value is true.

successFunc

A function that will be executed if request is executed successfully.
Function prototype: "successFunc(twainDevice)", where 'twainDevice' parameter is an instance of WebTwainDeviceJS class.

errorFunc

A function that will be executed if request is failed.
Function prototype: "errorFunc(twainDevice, errorMessage)", where 'twainDevice' parameter is an instance of WebTwainDeviceJS class, 'errorMessage' parameter is string that describes error.

This function sends an asynchronous request to open TWAIN device. If you want to use synchronous request instead of asynchronous request, please use WebTwainDeviceJS.open function.

Reference

WebTwainDeviceJS Class
WebTwainDeviceJS Members