Storage

BaselineWidely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

TheStorage interface of theWeb Storage API provides access to a particular domain's session or local storage. It allows, for example, the addition, modification, or deletion of stored data items.

To manipulate, for instance, the session storage for a domain, a call toWindow.sessionStorage is made; whereas for local storage the call is made toWindow.localStorage.

Instance properties

Storage.lengthRead only: Returns an integer representing the number of data items stored in theStorage object.

Instance methods

Storage.key(): When passed a numbern, this method will return the name of the nth key in the storage.
Storage.getItem(): When passed a key name, will return that key's value.
Storage.setItem(): When passed a key name and value, will add that key to the storage, or update that key's value if it already exists.
Storage.removeItem(): When passed a key name, will remove that key from the storage.
Storage.clear(): When invoked, will empty all keys out of the storage.

Here we access aStorage object by callinglocalStorage. We first test whether the local storage contains data items using!localStorage.getItem('bgcolor'). If it does, we run a function calledsetStyles() that grabs the data items usingStorage.getItem() and uses those values to update page styles. If it doesn't, we run another function,populateStorage(), which usesStorage.setItem() to set the item values, then runssetStyles().

if (!localStorage.getItem("bgcolor")) {  populateStorage();} else {  setStyles();}function populateStorage() {  localStorage.setItem("bgcolor", document.getElementById("bgcolor").value);  localStorage.setItem("font", document.getElementById("font").value);  localStorage.setItem("image", document.getElementById("image").value);  setStyles();}function setStyles() {  const currentColor = localStorage.getItem("bgcolor");  const currentFont = localStorage.getItem("font");  const currentImage = localStorage.getItem("image");  document.getElementById("bgcolor").value = currentColor;  document.getElementById("font").value = currentFont;  document.getElementById("image").value = currentImage;  htmlElem.style.backgroundColor = `#${currentColor}`;  pElem.style.fontFamily = currentFont;  imgElem.setAttribute("src", currentImage);}

Note:To see this running as a complete working example, see ourWeb Storage Demo.