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Created December 13, 2015 00:20
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LocalStorage JavaScript Module
/**
* Check if localStorage is supported const isSupported: boolean
* Check if localStorage has an Item function hasItem(key: string): boolean
* Get the amount of space left in localStorage function getRemainingSpace(): number
* Get the maximum amount of space in localStorage function getMaximumSpace(): number
* Get the used space in localStorage function getUsedSpace(): number
* Backup Assosiative Array interface Backup
* Get a Backup of localStorage function getBackup(): Backup
* Apply a Backup to localStorage function applyBackup(backup: Backup, fClear: boolean = true, fOverwriteExisting: boolean = true)
* Dump all information of localStorage in the console function consoleInfo(fShowMaximumSize: boolean = false)
*/
var LocalStorage;
(function (LocalStorage) {
/**
* Flag set true if the Browser supports localStorage
*/
LocalStorage.isSupported = (function () {
try {
var itemBackup = localStorage.getItem("");
localStorage.removeItem("");
localStorage.setItem("", itemBackup);
if (itemBackup === null)
localStorage.removeItem("");
else
localStorage.setItem("", itemBackup);
return true;
}
catch (e) {
return false;
}
})();
/**
* Check if localStorage has an Item / exists with the give key
* @param key the key of the Item
*/
function hasItem(key) {
return localStorage.getItem(key) !== null;
}
LocalStorage.hasItem = hasItem;
/**
* This will return the left space in localStorage without affecting it's content
* Might be slow !!!
*/
function getRemainingSpace() {
var itemBackup = localStorage.getItem("");
var increase = true;
var data = "1";
var totalData = "";
var trytotalData = "";
while (true) {
try {
trytotalData = totalData + data;
localStorage.setItem("", trytotalData);
totalData = trytotalData;
if (increase)
data += data;
}
catch (e) {
if (data.length < 2) {
break;
}
increase = false;
data = data.substr(data.length / 2);
}
}
if (itemBackup === null)
localStorage.removeItem("");
else
localStorage.setItem("", itemBackup);
return totalData.length;
}
LocalStorage.getRemainingSpace = getRemainingSpace;
/**
* This function returns the maximum size of localStorage without affecting it's content
* Might be slow !!!
*/
function getMaximumSpace() {
var backup = getBackup();
localStorage.clear();
var max = getRemainingSpace();
applyBackup(backup);
return max;
}
LocalStorage.getMaximumSpace = getMaximumSpace;
/**
* This will return the currently used size of localStorage
*/
function getUsedSpace() {
var sum = 0;
for (var key in localStorage) {
var value = localStorage.getItem(key);
sum += key.length + value.length;
}
return sum;
}
LocalStorage.getUsedSpace = getUsedSpace;
/**
* This will return a localStorage-backup (Associative-Array key->value)
*/
function getBackup() {
var backup = {};
for (var i = 0; i < localStorage.length; ++i) {
var key = localStorage.key(i);
var value = localStorage.getItem(key);
backup[key] = value;
}
return backup;
}
LocalStorage.getBackup = getBackup;
/**
* This will apply a localStorage-Backup (Associative-Array key->value)
* @param backup associative-array
* @param fClear optional flag to clear all existing storage first. Default: true
* @param fOverwriteExisting optional flag to replace existing keys. Default: true
*/
function applyBackup(backup, fClear, fOverwriteExisting) {
if (fClear === void 0) { fClear = true; }
if (fOverwriteExisting === void 0) { fOverwriteExisting = true; }
if (fClear == true) {
localStorage.clear();
}
for (var key in backup) {
if (fOverwriteExisting === false && backup[key] !== undefined) {
continue;
}
var value = backup[key];
localStorage.setItem(key, value);
}
}
LocalStorage.applyBackup = applyBackup;
/**
* This functions dumps all keys and values of the local Storage to the console,
* as well as the current size and number of items
* @param fShowMaximumSize optional, flag show maximum size of localStorage. Default: false
*/
function consoleInfo(fShowMaximumSize) {
if (fShowMaximumSize === void 0) { fShowMaximumSize = false; }
var amount = 0;
var size = 0;
for (var key in window.localStorage) {
var value = localStorage.getItem(key);
console.log(amount, key, value);
size += key.length + value.length;
amount++;
}
console.log("Total entries:", amount);
console.log("Total size:", size);
if (fShowMaximumSize === true) {
var maxSize = getMaximumSpace();
console.log("Total size:", maxSize);
}
}
LocalStorage.consoleInfo = consoleInfo;
})(LocalStorage || (LocalStorage = {}));
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