Generate random password string with requirements in javascript

Question

I want to generate a random string that has to have 5 letters from a-z and 3 numbers.

How can I do this with JavaScript?

I\'ve got the following script, but

Answer 1

var Password = {
 
  _pattern : /[a-zA-Z0-9_\-\+\.]/,
  
  
  _getRandomByte : function()
  {
    // http://caniuse.com/#feat=getrandomvalues
    if(window.crypto && window.crypto.getRandomValues) 
    {
      var result = new Uint8Array(1);
      window.crypto.getRandomValues(result);
      return result[0];
    }
    else if(window.msCrypto && window.msCrypto.getRandomValues) 
    {
      var result = new Uint8Array(1);
      window.msCrypto.getRandomValues(result);
      return result[0];
    }
    else
    {
      return Math.floor(Math.random() * 256);
    }
  },
  
  generate : function(length)
  {
    return Array.apply(null, {'length': length})
      .map(function()
      {
        var result;
        while(true) 
        {
          result = String.fromCharCode(this._getRandomByte());
          if(this._pattern.test(result))
          {
            return result;
          }
        }        
      }, this)
      .join('');  
  }    
    
};

<input type='text' id='p'/><br/>
<input type='button' value ='generate' onclick='document.getElementById("p").value = Password.generate(16)'>

Answer 2

Ok so if I understand well you're trying to get a random string password which contains 5 letters and 3 numbers randomly positioned and so which has a length of 8 characters and you accept maj and min letters, you can do that with the following function:

function randPass(lettersLength,numbersLength) {
    var j, x, i;
    var result           = '';
    var letters       = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
    var numbers       = '0123456789';
    for (i = 0; i < lettersLength; i++ ) {
        result += letters.charAt(Math.floor(Math.random() * letters.length));
    }
    for (i = 0; i < numbersLength; i++ ) {
        result += numbers.charAt(Math.floor(Math.random() * numbers.length));
    }
    result = result.split("");
    for (i = result.length - 1; i > 0; i--) {
        j = Math.floor(Math.random() * (i + 1));
        x = result[i];
        result[i] = result[j];
        result[j] = x;
    }
    result = result.join("");
    return result
}

function randPass(lettersLength,numbersLength) {
    var j, x, i;
    var result           = '';
    var letters       = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
    var numbers       = '0123456789';
    for (i = 0; i < lettersLength; i++ ) {
        result += letters.charAt(Math.floor(Math.random() * letters.length));
    }
    for (i = 0; i < numbersLength; i++ ) {
        result += numbers.charAt(Math.floor(Math.random() * numbers.length));
    }
    result = result.split("");
    for (i = result.length - 1; i > 0; i--) {
        j = Math.floor(Math.random() * (i + 1));
        x = result[i];
        result[i] = result[j];
        result[j] = x;
    }
    result = result.join("");
    return result
}
console.log(randPass(5,3))

Answer 3

Forcing a fixed number of characters is a bad idea. It doesn't improve the quality of the password. Worse, it reduces the number of possible passwords, so that hacking by bruteforcing becomes easier.

To generate a random word consisting of alphanumeric characters, use:

var randomstring = Math.random().toString(36).slice(-8);

How does it work?

Math.random()                        // Generate random number, eg: 0.123456
             .toString(36)           // Convert  to base-36 : "0.4fzyo82mvyr"
                          .slice(-8);// Cut off last 8 characters : "yo82mvyr"

Documentation for the Number.prototype.toString and string.prototype.slice methods.

Answer 4

And finally, without using floating point hacks:

function genpasswd(n) {
    // 36 ** 11 > Number.MAX_SAFE_INTEGER
    if (n > 10)
        throw new Error('Too big n for this function');
    var x = "0000000000" + Math.floor(Number.MAX_SAFE_INTEGER * Math.random()).toString(36);
    return x.slice(-n);
}

Answer 5

Create a Password generator service called PassswordGeneratorService

import { Injectable } from '@angular/core';

@Injectable()
export class PasswordGeneratorService {

  generatePassword(length:number,upper:boolean,numbers:boolean,symbols:boolean) {
    const passwordLength = length || 12;
    const addUpper =  upper;
    const addNumbers =  numbers;
    const addSymbols =  symbols;

    const lowerCharacters = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'];
    const upperCharacters = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'];
    const numbers = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9'];
    const symbols = ['!', '?', '@'];

    const getRandom = array => array[Math.floor(Math.random() * array.length)];

    let finalCharacters = '';

    if (addUpper) {
      finalCharacters = finalCharacters.concat(getRandom(upperCharacters));
    }

    if (addNumbers) {
      finalCharacters = finalCharacters.concat(getRandom(numbers));
    }

    if (addSymbols) {
      finalCharacters = finalCharacters.concat(getRandom(symbols));
    }

    for (let i = 1; i < passwordLength - 3; i++) {
      finalCharacters = finalCharacters.concat(getRandom(lowerCharacters));
    }

    return  finalCharacters.split('').sort(() => 0.5 - Math.random()).join('');
  }
}

don't forget to add the service on the module your using

@NgModule({
  imports: [
    CommonModule,
    SharedModule,
    CommonModule,
    RouterModule.forChild(routes),
    FormsModule,
    ReactiveFormsModule,
    FlexLayoutModule,
    TranslateModule,
    ExistingUserDialogModule,
    UserDocumentsUploadDialogModule
  ],
  declarations: [
    UserListComponent,
    EditUserDialogComponent,
    UserEditorComponent
  ],
  entryComponents: [
    EditUserDialogComponent
  ],
  providers: [
    AuthService,
    PasswordGeneratorService
  ]
})
export class UsersModule {
}

On you controller add a method which calls the generate password method inside the service and set the result on the password field

  constructor(
     private passwordGenerator: PasswordGeneratorService,
    )
  get newPassword() {
    return this.password.get('newPassword');
  }
  generatePassword() {
    this.newPassword.setValue(this.passwordGenerator.generatePassword(8,true,true,true));
  }

Answer 6

Secure password with one upperCase char.

let once = false;

    let newPassword = Math.random().toString(36).substr(2, 8).split('').map((char) => {
                    if(!Number(char) && !once){
                        once = true;
                        return char.toUpperCase();
                    }
                    return char;
                }).join('');

    console.log(newPassword)