var instance = new Vintasoft.Twain.WebTwainDeviceAcquireModalResultJS(acquireModalState, imageAcquiringProgressValue, acquiredImage, errorMessage);

var value; // Type: number
value = instance.get_ImageAcquiringProgressValue();

function get_ImageAcquiringProgressValue() : number;

The progress, in percents, of synchronous image acquisition process if acquireModalState == WebTwainAcquireModalStateEnumJS.ImageAcquiringProgress and TransferMode == WebTwainTransferModeEnumJS.Memory; otherwise, null.