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So I'm working on this project where I export some data files with sensitive information and I want to generate uuid for each of them. I'm using node uuid module but every time I run my function the UUID is actually the same and old file gets overwritten with a new file as its UUID is the same. Here's snipped of my code:

var nodeUuid = require('node-uuid');
var uuid = nodeUuid.v4();

function createFile(){
    var filename = 'reports-'+uuid+'.txt';
}
...
createFile();

So every time I call function createFile() I get the same UUID and my files are getting over-written, any idea how I could actually generate unique id for every new file?

So I'm working on this project where I export some data files with sensitive information and I want to generate uuid for each of them. I'm using node uuid module but every time I run my function the UUID is actually the same and old file gets overwritten with a new file as its UUID is the same. Here's snipped of my code:

var nodeUuid = require('node-uuid');
var uuid = nodeUuid.v4();

function createFile(){
    var filename = 'reports-'+uuid+'.txt';
}
...
createFile();

So every time I call function createFile() I get the same UUID and my files are getting over-written, any idea how I could actually generate unique id for every new file?

• javascript
• node.js
• uuid

Share Improve this question Follow asked Oct 23, 2015 at 10:42 TomasTomas 1,14122 gold badges1212 silver badges2525 bronze badges 1

• Its quite weird as I tried it in empty document and it generates unique Id every time function gets called.. – Tomas Commented Oct 23, 2015 at 10:51

Add a ment  | 

3 Answers 3

Sorted by: Reset to default 6

Move v4() call in to the function

function createFile(){
    var uuid = nodeUuid.v4();
    var filename = 'reports-'+uuid+'.txt';
}

Currently you're only generating a single UUID when the script is first loaded. To generate a new one each time you call createFile(), simply move the generation inside your createFile() function:

var nodeUuid = require('node-uuid');

function createFile(){
    var uuid = nodeUuid.v4();
    var filename = 'reports-'+uuid+'.txt';
}

...
createFile();

I might be late to the party, but you can do this without a library: The script below is the minified version of node-uuid v4 only library

import { default as crypto } from 'crypto'

class _Uuid {
    static v4(offset = 0){
        let byteToHex = [], rnds = crypto.randomBytes(16)

            rnds[6] = (rnds[6] & 0x0f) | 0x40 // Per 4.4, set bits for version and `clock_seq_hi_and_reserved`
            rnds[8] = (rnds[8] & 0x3f) | 0x80 // Per 4.4, set bits for version and `clock_seq_hi_and_reserved`

        for (var i = 0; i < 256; ++i) { byteToHex[i] = (i + 0x100).toString(16).substr(1) }

        return ([byteToHex[rnds[offset++]], byteToHex[rnds[offset++]], byteToHex[rnds[offset++]], byteToHex[rnds[offset++]], '-', byteToHex[rnds[offset++]], byteToHex[rnds[offset++]], '-', byteToHex[rnds[offset++]], byteToHex[rnds[offset++]], '-', byteToHex[rnds[offset++]], byteToHex[rnds[offset++]], '-', byteToHex[rnds[offset++]], byteToHex[rnds[offset++]], byteToHex[rnds[offset++]], byteToHex[rnds[offset++]], byteToHex[rnds[offset++]], byteToHex[rnds[offset++]]]).join('')  
    }
}

const v4 = _Uuid.v4

export { v4 as default }

Usage

import { default as uuid } from '_Uuid'

uuid() // 3ceb4f8f-cef9-400f-a394-80da0334273b

This is an ES6 script that uses the bundled crypto library in node and facilitates simple, fast generation of RFC4122 pliant v4 UUIDS. Source Code

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