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Replace var with let/const in examples
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Slightly modernize the example code, and fixes an issue noted in:
#209 (comment)
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@inexorabletash
inexorabletash authored Sep 24, 2019
1 parent d3943e1 commit 6f17004
Showing 1 changed file with 49 additions and 47 deletions.
96 changes: 49 additions & 47 deletions index.bs
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Original file line number Diff line number Diff line change
Expand Up @@ -142,14 +142,15 @@ object store and indexes. Finally, the opened connection is saved for
use in subsequent examples.

```js
var request = indexedDB.open("library");
const request = indexedDB.open("library");
let db;

request.onupgradeneeded = function() {
// The database did not previously exist, so create object stores and indexes.
var db = request.result;
var store = db.createObjectStore("books", {keyPath: "isbn"});
var titleIndex = store.createIndex("by_title", "title", {unique: true});
var authorIndex = store.createIndex("by_author", "author");
const db = request.result;
const store = db.createObjectStore("books", {keyPath: "isbn"});
const titleIndex = store.createIndex("by_title", "title", {unique: true});
const authorIndex = store.createIndex("by_author", "author");

// Populate with initial data.
store.put({title: "Quarry Memories", author: "Fred", isbn: 123456});
Expand All @@ -165,8 +166,8 @@ request.onsuccess = function() {
The following example populates the database using a transaction.

```js
var tx = db.transaction("books", "readwrite");
var store = tx.objectStore("books");
const tx = db.transaction("books", "readwrite");
const store = tx.objectStore("books");

store.put({title: "Quarry Memories", author: "Fred", isbn: 123456});
store.put({title: "Water Buffaloes", author: "Fred", isbn: 234567});
Expand All @@ -181,13 +182,13 @@ The following example looks up a single book in the database by title
using an index.

```js
var tx = db.transaction("books", "readonly");
var store = tx.objectStore("books");
var index = store.index("by_title");
const tx = db.transaction("books", "readonly");
const store = tx.objectStore("books");
const index = store.index("by_title");

var request = index.get("Bedrock Nights");
const request = index.get("Bedrock Nights");
request.onsuccess = function() {
var matching = request.result;
const matching = request.result;
if (matching !== undefined) {
// A match was found.
report(matching.isbn, matching.title, matching.author);
Expand All @@ -202,13 +203,13 @@ The following example looks up all books in the database by author
using an index and a cursor.

```js
var tx = db.transaction("books", "readonly");
var store = tx.objectStore("books");
var index = store.index("by_author");
const tx = db.transaction("books", "readonly");
const store = tx.objectStore("books");
const index = store.index("by_author");

var request = index.openCursor(IDBKeyRange.only("Fred"));
const request = index.openCursor(IDBKeyRange.only("Fred"));
request.onsuccess = function() {
var cursor = request.result;
const cursor = request.result;
if (cursor) {
// Called for each matching record.
report(cursor.value.isbn, cursor.value.title, cursor.value.author);
Expand All @@ -224,9 +225,9 @@ The following example shows how errors could be handled when a request
fails.

```js
var tx = db.transaction("books", "readwrite");
var store = tx.objectStore("books");
var request = store.put({title: "Water Buffaloes", author: "Slate", isbn: 987654});
const tx = db.transaction("books", "readwrite");
const store = tx.objectStore("books");
const request = store.put({title: "Water Buffaloes", author: "Slate", isbn: 987654});
request.onerror = function(event) {
// The uniqueness constraint of the "by_title" index failed.
report(request.error);
Expand All @@ -249,26 +250,27 @@ stores and indexes. The following example shows one way to handle
migrating from an older version of the database.

```js
var request = indexedDB.open("library", 3); // Request version 3.
const request = indexedDB.open("library", 3); // Request version 3.
let db;

request.onupgradeneeded = function(event) {
var db = request.result;
const db = request.result;
if (event.oldVersion < 1) {
// Version 1 is the first version of the database.
var store = db.createObjectStore("books", {keyPath: "isbn"});
var titleIndex = store.createIndex("by_title", "title", {unique: true});
var authorIndex = store.createIndex("by_author", "author");
const store = db.createObjectStore("books", {keyPath: "isbn"});
const titleIndex = store.createIndex("by_title", "title", {unique: true});
const authorIndex = store.createIndex("by_author", "author");
}
if (event.oldVersion < 2) {
// Version 2 introduces a new index of books by year.
var bookStore = request.transaction.objectStore("books");
var yearIndex = bookStore.createIndex("by_year", "year");
const bookStore = request.transaction.objectStore("books");
const yearIndex = bookStore.createIndex("by_year", "year");
}
if (event.oldVersion < 3) {
// Version 3 introduces a new object store for magazines with two indexes.
var magazines = db.createObjectStore("magazines");
var publisherIndex = magazines.createIndex("by_publisher", "publisher");
var frequencyIndex = magazines.createIndex("by_frequency", "frequency");
const magazines = db.createObjectStore("magazines");
const publisherIndex = magazines.createIndex("by_publisher", "publisher");
const frequencyIndex = magazines.createIndex("by_frequency", "frequency");
}
};

Expand Down Expand Up @@ -342,8 +344,8 @@ event fires if other clients still hold a connection to the database after their
<a event>`versionchange`</a> events have fired.

```js
var request = indexedDB.open("library", 4); // Request version 4.
var blockedTimeout;
const request = indexedDB.open("library", 4); // Request version 4.
let blockedTimeout;

request.onblocked = function() {
// Give the other clients time to save data asynchronously.
Expand Down Expand Up @@ -1754,10 +1756,10 @@ property is assigned a value of 1 because that is the next [=/key=]
generated by the [=key generator=].

```js
var store = db.createObjectStore("store", { keyPath: "foo.bar",
autoIncrement: true });
const store = db.createObjectStore("store", { keyPath: "foo.bar",
autoIncrement: true });
store.put({ foo: {} }).onsuccess = function(e) {
var key = e.target.result;
const key = e.target.result;
console.assert(key === 1);
};
```
Expand All @@ -1779,10 +1781,10 @@ store=] is "`foo.bar`". The actual object has a value of
key value.

```js
var store = db.createObjectStore("store", { keyPath: "foo.bar",
autoIncrement: true });
const store = db.createObjectStore("store", { keyPath: "foo.bar",
autoIncrement: true });
store.put({ foo: { bar: 10 } }).onsuccess = function(e) {
var key = e.target.result;
const key = e.target.result;
console.assert(key === 10);
};
```
Expand All @@ -1804,13 +1806,13 @@ properties are created each as a child of the other until a value for
store.

```js
var store = db.createObjectStore("store", { keyPath: "foo.bar.baz",
autoIncrement: true });
const store = db.createObjectStore("store", { keyPath: "foo.bar.baz",
autoIncrement: true });
store.put({ zip: {} }).onsuccess = function(e) {
var key = e.target.result;
const key = e.target.result;
console.assert(key === 1);
store.get(key).onsuccess = function(e) {
var value = e.target.result;
const value = e.target.result;
// value will be: { zip: {}, foo: { bar: { baz: 1 } } }
console.assert(value.foo.bar.baz === 1);
};
Expand All @@ -1827,7 +1829,7 @@ the actual object is an array, `[10]`. Trying to define a
property on the array fails.

```js
var store = db.createObjectStore("store", { keyPath: "foo", autoIncrement: true });
const store = db.createObjectStore("store", { keyPath: "foo", autoIncrement: true });

// The key generation will attempt to create and store the key path
// property on this primitive.
Expand Down Expand Up @@ -1980,7 +1982,7 @@ Various event handlers are registered for responding to various
situations.

```js
var request = indexedDB.open('AddressBook', 15);
const request = indexedDB.open('AddressBook', 15);
request.onsuccess = function(evt) {...};
request.onerror = function(evt) {...};
```
Expand Down Expand Up @@ -3595,9 +3597,9 @@ must be used as error.
The asynchronous creation of indexes is observable in the following example:

```js
var request1 = objectStore.put({name: "betty"}, 1);
var request2 = objectStore.put({name: "betty"}, 2);
var index = objectStore.createIndex("by_name", "name", {unique: true});
const request1 = objectStore.put({name: "betty"}, 1);
const request2 = objectStore.put({name: "betty"}, 2);
const index = objectStore.createIndex("by_name", "name", {unique: true});
```

At the point where {{createIndex()}} called, neither of the
Expand Down

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