1. Web
  2. Web APIs
  3. WorkletSharedStorage
  4. get()

WorkletSharedStorage: get() method

Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.

The get() method of the WorkletSharedStorage interface retrieves a value from shared storage.

Syntax

js
get(key)

Parameters

key

A string representing the key of the key-value pair you want to retrieve.

Return value

A Promise that fulfills with either a string equal to the value of the retrieved key-value pair or undefined if the specified key is not found in the shared storage.

Exceptions

TypeError

Thrown if:

Examples

Measuring K+ frequency

The following example measures the K+ frequency of content views. Sometimes described as "effective frequency", K frequency refers to the minimum number of views before a user will recognize or recall certain content (often used in the context of ad views).

The main page script:

js
// k-frequency-measurement.js

async function injectContent() {
  // Load the Shared Storage worklet
  await window.sharedStorage.worklet.addModule("k-freq-measurement-worklet.js");

  // Run the K-frequency measurement operation
  await window.sharedStorage.run("k-freq-measurement", {
    data: { kFreq: 3, contentId: 123 },
  });
}

injectContent();

The worklet module is shown below:

js
// k-frequency-measurement-worklet.js

// Scale factor for handling noise added to data
const SCALE_FACTOR = 65536;

/**
 * The bucket key must be a number, and in this case, it is simply the content
 * ID itself. For more complex bucket key construction, see other use cases in
 * this demo.
 */
function convertContentIdToBucket(contentId) {
  return BigInt(contentId);
}

class KFreqMeasurementOperation {
  async run(data) {
    const { kFreq, contentId } = data;

    // Read from Shared Storage
    const hasReportedContentKey = "has-reported-content";
    const impressionCountKey = "impression-count";
    const hasReportedContent =
      (await this.sharedStorage.get(hasReportedContentKey)) === "true";
    const impressionCount = parseInt(
      (await this.sharedStorage.get(impressionCountKey)) || 0,
      10,
    );

    // Do not report if a report has been sent already
    if (hasReportedContent) {
      return;
    }

    // Check impression count against frequency limit
    if (impressionCount < kFreq) {
      await this.sharedStorage.set(impressionCountKey, impressionCount + 1);
      return;
    }

    // Generate the aggregation key and the aggregatable value
    const bucket = convertContentIdToBucket(contentId);
    const value = 1 * SCALE_FACTOR;

    // Send an aggregatable report via the Private Aggregation API
    privateAggregation.sendHistogramReport({ bucket, value });

    // Set the report submission status flag
    await this.sharedStorage.set(hasReportedContentKey, "true");
  }
}

// Register the operation
register("k-freq-measurement", KFreqMeasurementOperation);

For more details about this example, see K+ frequency measurement. See the Shared Storage API landing page for links to other examples.

Specifications

This feature does not appear to be defined in any specification.

Browser compatibility

See also

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