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JavaScript API Reference

The primary class of the library is LabelRecognizer . The following code snippets shows the basic usage.

Recognize a still image

let labelRecognizer = await Dynamsoft.DLR.LabelRecognizer.createInstance();
let results = await labelRecognizer.recognize(imagePath);
for (let result of results) {
    for (let lineResult of result.lineResults) {
        console.log(lineResult.text);
    }
}

Recognize continuous video frames

let cameraEnhancer = await Dynamsoft.DCE.CameraEnhancer.createInstance();
await cameraEnhancer.setUIElement(document.getElementById('div-ui-container'));
let recognizer = await Dynamsoft.DLR.LabelRecognizer.createInstance();
recognizer.setImageSource(cameraEnhancer);
await recognizer.updateRuntimeSettingsFromString("video-MRZ");
labelRecognizer.onImageRead = results => {
    for (let result of results) {
        for (let lineResult of result.lineResults) {
            console.log(lineResult.text);
        }
    }
};
labelRecognizer.startScanning(true);

The APIs for this class include

Initialization Control

The following static methods and properties help to set up the runtime environment for the library.

API Name	Description
engineResourcePath	Specifies the path from where the recognition engine and models, etc. can be loaded.
loadWasm()	Loads the recognition engine and models.
isWasmLoaded()	Returns whether the recognition engine and models have been loaded.
getVersion()	Returns the version of the library.
detectEnvironment()	Assess the running environment regarding the features the library requires to run.

Create and Destroy Instances

API Name	Description
createInstance()	Creates a `LabelRecognizer` instance.
destroyContext()	Destroies the LabelRecognizer instance.
isContextDestroyed()	Returns whether the instance has been destroyed.

License Control

API Name	Description
license	Use an alphanumeric string to specify the license.

Recognition

Recognize Labels from Still Images

API Name	Description
recognize()	Decodes labels from an image.
recognizeBase64String()	Decodes labels from a base64-encoded image (with or without MIME).
recognizeUrl()	Decodes labels from an image specified by its URL.
recognizeBuffer()	Decodes labels from raw image data.

Recognize Labels from Video Frames

API Name	Description
setImageSource	Sets an image source for continous scanning.
onUniqueRead	This event is triggered when a new, unduplicated label is found.
onImageRead	This event is triggered after the library finishes scanning an image.
onMRZRead	This event is triggered after the library finishes scanning a frame with the built-in templates `passportMRZ` , `video-passportMRZ` , `visaMRZ` , `video-visaMRZ` , `MRZ` or `video-MRZ` .
onVINRead	This event is triggered after the library finishes scanning an image based on one of the built-in templates `VIN`, `video-VIN`, `VIN_NA` or `video-VIN_NA`.
startScanning()	Starts continuous scanning of incoming images.
stopScanning()	Stops continuous scanning.
pauseScanning()	Pause continuous scanning but keep the video stream.
resumeScanning()	Resumes continuous scanning.

Settings

Scan Settings

API Name	Description
getScanSettings()	Returns the current scan settings.
updateScanSettings()	Changes scan settings with the object passed in.

Runtime Settings

API Name	Description
updateRuntimeSettingsFromString()	Updates runtime settings with a template represented by a JSON string.
outputRuntimeSettingsToString()	Output the current runtime settings to a JSON string.
updateReferenceRegionFromBarcodeResults()	Updates reference region which is defined with source type `DLR_LST_BARCODE`.

Auxiliary

API Name	Description
ifSaveOriginalImageInACanvas	Whether to save the original image into a < canvas> element.
getOriginalImageInACanvas()	Returns an `HTMLCanvasElement` that holds the original image.
onResourcesLoadStarted	This event is triggered when the resource file (.data) for a particular template starts to load.
onResourcesLoadProgress	This event is triggered multiple times when the resource file (.data) for a particular template is being loaded.
onResourcesLoaded	This event is triggered when the resource file (.data) for a particular template finishes loading.

Interfaces and Enumerations

In order to make the code more predictable and readable, the library defines a series of supporting interfaces and enumerations.