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@6174
Created July 23, 2013 13:36
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Generate a random string in JavaScript In a short and fast way!
//http://stackoverflow.com/questions/105034/how-to-create-a-guid-uuid-in-javascript
Math.random().toString(36).substring(2, 15) + Math.random().toString(36).substring(2, 15);
@sempostma
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sempostma commented Feb 28, 2020

Silly oneliners:

[a-zA-Z0-9]:

for(var a = ''; a.length < 40;) a += "0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz"[(Math.random() * 60) | 0]

[0-z]

String.fromCharCode.apply(0, Array(40).fill(0).map(() => Math.random() * 74 + 42) | 0)

[0-9a-z]

for(var a = '', b = 36; a.length < 40;) a += (Math.random() * b | 0).toString(b)

[0-9A-Z]

for(var a = ''; r = Math.random() * 42, a.length < 40;) a += r < 10 || r > 16 ? String.fromCharCode(48 + r | 0) : ''

@radicand
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Using crypto: crypto.randomBytes(32).toString('base64'), adjust the parameter to randomBytes for the length you need.

@josuerodcat90
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Perfect, thank you!

@rherugu
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rherugu commented May 14, 2020

nice

@abhidp
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abhidp commented Jul 25, 2020

[...Array(10)].map(i=>(~~(Math.random()*36)).toString(36)).join('')

this is a little better, you can specify any length 💪

where is the i being used? better off providing an empty function like this?

const randomString = (length) => [ ...Array(length) ].map(() => (~~(Math.random() * 36)).toString(36)).join('');

console.log(randomString(14));

@mmRoshani
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that's good, thanks😊

@jwpjrdev
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jwpjrdev commented Sep 3, 2020

So simple, so useful.

@pparadoxx
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thank you so much 👍

@VhMuzini
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VhMuzini commented Oct 5, 2020

Thank you

@MisaGu
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MisaGu commented Oct 6, 2020

Array.from({length:10}, () => String.fromCharCode(String(parseInt(65 + Math.random() * (122 - 65))).replace(/9[1-6]/,'90'))).join('')

@abhijit666
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Is there any simple way to generate string without numbers in it?

@jonathan-annett
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Is there any simple way to generate string without numbers in it?

const randcharset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

const randchars = (function (R,M) {
    var L = R.length,r=M.random, f= M.floor;
    return function (len) {
        var i,s="";
        for (i=0;i<len;i++) s += R[f(r() * L)];
        return s;
    };
})(randcharset.split(''),Math);

for example

document.write("hello:"+randchars(4));

@adam-cyclones
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"doadiahdoiawd"

Of course you would have to type sporadically every time but I believe this is the fastest performing solution.

@s3rgeym
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s3rgeym commented Jan 26, 2021

// only printable
Array(8).fill().map(_ => String.fromCharCode(33 + Math.random() * (127 - 33))).join('')

@migue802
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Noice. 👌 Thanks!!

@usayamadx
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Awesome!!!

@BlueProgrammer212
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Pretty cool!

@KnJbMfLAgdkwZL
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Brilliant!

@Montazu
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Montazu commented Jan 6, 2022

This is my version. Generate random string with numbers, lower and upper case.

const randomString=length=>Math.random().toString(36).substr(2,length).split("").map(e=>Math.random()<Math.random()?e.toUpperCase():e).join().replaceAll(",","");

console.log(randomString(10)); //8itPVoPBdU

@ughitsaaron
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Using recursion with the option of providing a prefix.

function randomStr(minLength = 0, acc = '') {
    if (acc.length <= minLength) {
        const str = Math.random().toString(36).slice(2);
        return randomStr(minLength, acc.concat(str))
    }

    return acc.slice(0, minLength);
}

randomStr(10) // => 'fvaj2hm2na'
randomStr(30, 'https://short.codes/') // => 'https://short.codes/jtmx66qr06'

@zeelkakdiya
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  const idString = async (string_length) => {
    var random_str = "";
    var characters =
      "ABCDEFGHIJKLMNOPQRSTUVWXYZqeytrpolkadjsghfgmnbzxcvnQPOWEYRKASJHDGFMNBCVX--___-_jsfhrlg-_124903564576986483658fgh4sdfh687e4h897WETHJ68F7G4688471877GFHJFFGJ87469857468746hfghwrtiyj4598yhdjkhgnk";
    for (let index = 0; index < string_length; index++) {
      random_str += characters.charAt(
        Math.floor(Math.random() * characters.length)
      );
    }
    let string = `${random_str}`;
    console.log(string);
    return string;
  };

@adam-cyclones
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adam-cyclones commented Jul 6, 2022

@zeelkakdiya constructive feedback to improve this code:

  1. This is not an async function, it does not use promises
  2. var is used rather than let and in some cases const are more appropriate
  3. let string does not need ${}
  4. console.log is not useful in production code and actually slows down this function
  5. let string to return could be removed.
  6. casing is inconsistent
const generateID = (stringLength = 20) => {
    let randomStr = "";
    const characters = "ABCDEFGHIJKLMNOPQRSTUVWXYZqeytrpolkadjsghfgmnbzxcvnQPOWEYRKASJHDGFMNBCVX--___-_jsfhrlg-_124903564576986483658fgh4sdfh687e4h897WETHJ68F7G4688471877GFHJFFGJ87469857468746hfghwrtiyj4598yhdjkhgnk";
    for (let index = 0; index < stringLength; index++) {
      randomStr += characters.charAt(
        Math.floor(Math.random() * characters.length)
      );
    }
    return randomStr;
  };

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