index.md

title	LanguageDetector: detect() method
short-title	detect()
slug	Web/API/LanguageDetector/detect
page-type	web-api-instance-method
status	experimental
browser-compat	api.LanguageDetector.detect

{{APIRef("Translator and Language Detector APIs")}}{{SeeCompatTable}}{{securecontext_header}}

The detect() method of the {{domxref("LanguageDetector")}} interface detects the closest matching language or languages that a given text string is most likely to be written in.

Syntax

detect(input)
detect(input, options)

Parameters

• input
  • : A string representing the text to have its language detected.
• options {{optional_inline}}
  • : An object specifying configuration options for the detect() operation. Possible values include:
    • signal
      • : An {{domxref("AbortSignal")}} object instance, which allows the detect() operation to be aborted via the associated {{domxref("AbortController")}}.

Return value

A {{jsxref("Promise")}} that fulfills with an array of objects representing the detected languages. Each object contains the following properties:

• detectedLanguage
  • : A {{glossary("BCP 47 language tag")}} representing the detected language.
• confidence
  • : A number between 0 and 1 representing the AI model's confidence that the detected language is correct.

The sum of all the returned confidence values should theoretically be 1, however, it may be lower because very low confidence values are excluded from the results.

The last array element returned will always have a detectedLanguage value of und — this is an abbreviation of "undetermined", and represents the probability that the text is not written in a language the model knows.

Exceptions

• AbortError {{domxref("DOMException")}}
  • : Thrown if the LanguageDetector was previously destroyed (had {{domxref("LanguageDetector.destroy()")}} called on it, or was aborted via its abort signal after creation).
• InvalidStateError {{domxref("DOMException")}}
  • : Thrown if the current {{domxref("Document")}} is not active.
• {{domxref("QuotaExceededError")}}
  • : Thrown if the language detection operation exceeds the available {{domxref("LanguageDetector.inputQuota", "inputQuota")}}.

Examples

Basic detect() usage

const detector = await LanguageDetector.create({
  expectedInputLanguages: ["en-US", "zh"],
});

const results = await detector.detect(myTextString);

results.forEach((result) => {
  console.log(`${result.detectedLanguage}: ${result.confidence}`);
});

// Results in logs like this:
// la: 0.8359838724136353
// es: 0.017705978825688362
// sv: 0.012977192178368568
// en: 0.011148443445563316
// und: 0.0003214875760022551

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• Using the Translator and Language Detector APIs