W3cubDocs

/DOM

IDBCursor.continuePrimaryKey

The continuePrimaryKey() method of the IDBCursor interface advances the cursor to the to the item whose key matches the key parameter as well as whose primariy key matches the primary key parameter.

A typical use case, is to resume the iteration where a previous cursor has been closed, without having to compare the keys one by one.

Calling this method more than once before new cursor data has been loaded - for example, calling continuePrimaryKey() twice from the same onsuccess handler - results in an InvalidStateError being thrown on the second call because the cursor’s got value flag has been unset.

Note: This feature is available in Web Workers.

Syntax

cursor.continuePrimaryKey(key, primaryKey);

Parameters

key: The key to position the cursor at.
primaryKey: The primary key to position the cursor at.

Exceptions

This method may raise a DOMException of one of the following types:

Exception	Description
`TransactionInactiveError`	This IDBCursor's transaction is inactive.
`DataError`	The key parameter may have any of the following conditions: The key is not a valid key. The key is less than or equal to this cursor's position and the cursor's direction is `next` or `nextunique`. The key is greater than or equal to this cursor's position and this cursor's direction is `prev` or `prevunique`.
`InvalidStateError`	The cursor is currently being iterated or has iterated past its end.
`InvalidAccessError`	The cursor's direction is not `prev` or `next`.

Example

here’s how you can resume an iteration of all articles tagged with 'javascript' since your last visit:

let request = articleStore.index("tag").openCursor();
let count = 0;
let unreadList = [];
request.onsuccess = (event) => {
    let cursor = event.target.result;
    if (!cursor) { return; }
    let lastPrimaryKey = getLastIteratedArticleId();
    if (lastPrimaryKey > cursor.primaryKey) {
      cursor.continuePrimaryKey("javascript", lastPrimaryKey);
      return;
    }
    // update lastIteratedArticleId
    setLastIteratedArticleId(cursor.primaryKey);
    // preload 5 articles into the unread list;
    unreadList.push(cursor.value);
    if (++count < 5) {
      cursor.continue();
    }
};

Specifications

Specification	Status	Comment
Indexed Database API (Second Edition) The definition of 'continuePrimaryKey()' in that specification.	Editor's Draft	Initial definition.

Browser compatibility

Feature	Chrome	Firefox (Gecko)	Internet Explorer	Opera	Safari (WebKit)
Basic support	?	10 moz 51.0 (51.0)	?	?	?

Feature	Android	Firefox Mobile (Gecko)	IE Phone	Opera Mobile	Safari Mobile
Basic support	?	51.0 (51.0)	?	?	?