Secure context
This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.
The StorageEstimate dictionary's quota property is a conservative approximation of how much storage is allotted to the origin or Web app that called StorageManager.estimate(); there may be more space available, but there will not be less. This value is an estimate to help prevent its use for fingerprinting—that is, identifying a device using an amalgamation of the values of seemingly innocuous properties.
Syntax
quota = StorageEstimate.quota;
Value
A numeric value specifying an approximation of the total amount of storage space available for use by the application.
Example
In this example, we obtain the usage estimates and present the percentage of storage capacity currently used to the user.
HTML content
<p> You're currently using about <span id="percent"> </span>% of your available storage. </p>
JavaScript content
navigator.storage.estimate().then(function(estimate) {
document.getElementById("percent").innerHTML =
(estimate.usage / estimate.quota).toFixed(2);
});