@gorpacrate/core-graphics
Version:
A core library for creating shape-based graphic editors
50 lines • 2.07 kB
JavaScript
;
exports.__esModule = true;
var getUniquiId = (function () {
// Modeled after base64 web-safe chars, but ordered by ASCII.
var PUSH_CHARS = '-0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz';
// Timestamp of last push, used to prevent local collisions if you push twice in one ms.
var lastPushTime = 0;
// We generate 72-bits of randomness which get turned into 12 characters and appended to the
// timestamp to prevent collisions with other clients. We store the last characters we
// generated because in the event of a collision, we'll use those same characters except
// "incremented" by one.
var lastRandChars = [];
return function () {
var now = new Date().getTime();
var duplicateTime = (now === lastPushTime);
lastPushTime = now;
var timeStampChars = new Array(8);
for (var i = 7; i >= 0; i--) {
timeStampChars[i] = PUSH_CHARS.charAt(now % 64);
// NOTE: Can't use << here because javascript will convert to int and lose the upper bits.
now = Math.floor(now / 64);
}
if (now !== 0) {
throw new Error('We should have converted the entire timestamp.');
}
var id = timeStampChars.join('');
if (!duplicateTime) {
for (var i = 0; i < 4; i++) {
lastRandChars[i] = Math.floor(Math.random() * 64);
}
}
else {
// If the timestamp hasn't changed since last push, use the same random number, except incremented by 1.
var i = void 0;
for (i = 3; i >= 0 && lastRandChars[i] === 63; i--) {
lastRandChars[i] = 0;
}
lastRandChars[i]++;
}
for (var i = 0; i < 4; i++) {
id += PUSH_CHARS.charAt(lastRandChars[i]);
}
if (id.length !== 12) {
throw new Error('Length should be 12.');
}
return id;
};
})();
exports["default"] = getUniquiId;
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