# JavaScript: Function to create a UUID identifier

## JavaScript Math: Exercise-23 with Solution

Write a JavaScript function to create a UUID identifier.

Note :
According to Wikipedia - A universally unique identifier (UUID) is an identifier standard used in software construction. A UUID is simply a 128-bit value. The meaning of each bit is defined by any of several variants. For human-readable display, many systems use a canonical format using hexadecimal text with inserted hyphen characters. For example : de305d54-75b4-431b-adb2-eb6b9e546014

Sample Solution:

JavaScript Code:

``````// Define a function named create_UUID that generates a version 4 UUID.
function create_UUID(){
// Get the current time in milliseconds since the Unix epoch.
var dt = new Date().getTime();
// Replace the placeholders in the UUID template with random hexadecimal characters.
var uuid = 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
// Generate a random hexadecimal digit.
var r = (dt + Math.random()*16)%16 | 0;
// Update dt to simulate passage of time for the next random character.
dt = Math.floor(dt/16);
// Replace 'x' with a random digit and 'y' with a specific digit (4 for UUID version 4).
return (c=='x' ? r :(r&0x3|0x8)).toString(16);
});
// Return the generated UUID.
return uuid;
}

// Output a version 4 UUID to the console.
console.log(create_UUID());
```
```

Output:

```1fe35579-5ce7-46ec-89e0-7e7236700297
```

Flowchart:

Live Demo:

See the Pen javascript-math-exercise-23 by w3resource (@w3resource) on CodePen.

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