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@robnyman
Last active January 30, 2024 09:22
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Get file as an arraybuffer, create blob, read through FileReader and save in localStorage
// Getting a file through XMLHttpRequest as an arraybuffer and creating a Blob
var rhinoStorage = localStorage.getItem("rhino"),
rhino = document.getElementById("rhino");
if (rhinoStorage) {
// Reuse existing Data URL from localStorage
rhino.setAttribute("src", rhinoStorage);
}
else {
// Create XHR, Blob and FileReader objects
var xhr = new XMLHttpRequest(),
blob,
fileReader = new FileReader();
xhr.open("GET", "rhino.png", true);
// Set the responseType to arraybuffer. "blob" is an option too, rendering manual Blob creation unnecessary, but the support for "blob" is not widespread enough yet
xhr.responseType = "arraybuffer";
xhr.addEventListener("load", function () {
if (xhr.status === 200) {
// Create a blob from the response
blob = new Blob([xhr.response], {type: "image/png"});
// onload needed since Google Chrome doesn't support addEventListener for FileReader
fileReader.onload = function (evt) {
// Read out file contents as a Data URL
var result = evt.target.result;
// Set image src to Data URL
rhino.setAttribute("src", result);
// Store Data URL in localStorage
try {
localStorage.setItem("rhino", result);
}
catch (e) {
console.log("Storage failed: " + e);
}
};
// Load blob as Data URL
fileReader.readAsDataURL(blob);
}
}, false);
// Send XHR
xhr.send();
}
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Thanks

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