The bound()
method of the IDBKeyRange
interface creates a new key range with the specified upper and lower bounds. The bounds can be open (that is, the bounds exclude the endpoint values) or closed (that is, the bounds include the endpoint values). By default, the bounds are closed.
bound(lower, upper)
bound(lower, upper, lowerOpen)
bound(lower, upper, lowerOpen, upperOpen)
IDBKeyRange
: The newly created key range.
This method may raise a DOMException
of the following type:
The following example illustrates how you'd use a bound key range. Here we declare a keyRangeValue = IDBKeyRange.bound("A", "F");
— a range between values of "A" and "F". We open a transaction (using IDBTransaction
) and an object store, and open a Cursor with IDBObjectStore.openCursor
, declaring keyRangeValue
as its optional key range value. This means that the cursor will only retrieve records with keys inside that range. This range includes the values "A" and "F", as we haven't declared that they should be open bounds. If we used IDBKeyRange.bound("A", "F", true, true);
, then the range would not include "A"
and "F"
, only the values between them.
function displayData() {
var keyRangeValue = IDBKeyRange.bound("A", "F");
var transaction = db.transaction(['fThings'], 'readonly');
var objectStore = transaction.objectStore('fThings');
objectStore.openCursor(keyRangeValue).onsuccess = function(event) {
var cursor = event.target.result;
if(cursor) {
var listItem = document.createElement('li');
listItem.innerHTML = '<strong>' + cursor.value.fThing + '</strong>, ' + cursor.value.fRating;
list.appendChild(listItem);
cursor.continue();
} else {
console.log('Entries all displayed.');
}
};
};