Summarizer: length property

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

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The length read-only property of the Summarizer interface returns the relative length of the generated summaries.

Value

An enumerated value specifying the relative length of the generated summaries, the exact nature of which depends on the Summarizer type value.

Possible values are:

A "short" summary

For type tldr and teaser, the summary should fit into one sentence.
For type key-points, the summary should be no more than three bullet points.
For type headline, the summary should be no more than 12 words.

A "medium" summary

For type tldr and teaser, the summary should fit into one short paragraph.
For type key-points, the summary should be no more than five bullet points.
For type headline, the summary should be no more than 17 words.

A "long" summary

For type tldr and teaser, the summary should fit into one paragraph.
For type key-points, the summary should be no more than seven bullet points.
For type headline, the summary should be no more than 22 words.

const summarizer = await Summarizer.create({
  length: "medium",
  // ...
});

// Logs "medium"
console.log(summarizer.length);

Specification
Writing Assistance APIs # dom-summarizer-length

This page was last modified on ⁨Jul 13, 2025⁩ by MDN contributors.