I'm using the following typescript method to generate UUIDs. The code itself is basically the typescript version of this stackoverflow answer.

generateUUID(): string {
    let date = new Date().getTime();
    if (window.performance && typeof window.performance.now === 'function') {
        date += performance.now();
    }
    let uuid = 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
        let r = (date + Math.random() * 16) % 16 | 0;
        date = Math.floor(date / 16);
        return (c === 'x' ? r : (r & 0x3 | 0x8)).toString(16);
    });
    return uuid;
};

Our development team uses TSLint to keep the code clean and we have a rule that forbids to use bitwise operators. I have no idea how to rewrite this code without harming the cryptographic aspect of the UUID generator. How can this piece of code be rewritten or doesn't this make sense at all?

I'm using the following typescript method to generate UUIDs. The code itself is basically the typescript version of this stackoverflow answer.

generateUUID(): string {
    let date = new Date().getTime();
    if (window.performance && typeof window.performance.now === 'function') {
        date += performance.now();
    }
    let uuid = 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
        let r = (date + Math.random() * 16) % 16 | 0;
        date = Math.floor(date / 16);
        return (c === 'x' ? r : (r & 0x3 | 0x8)).toString(16);
    });
    return uuid;
};

Our development team uses TSLint to keep the code clean and we have a rule that forbids to use bitwise operators. I have no idea how to rewrite this code without harming the cryptographic aspect of the UUID generator. How can this piece of code be rewritten or doesn't this make sense at all?

• javascript
• typescript
• uuid
• lint
• tslint

• 4 Why on earth do you have a rule that forbids bitwise operators? That's weird. – Pointy Commented Dec 19, 2016 at 13:46
• I think it is weird as well, but this was not my decision. – Sebastian Krogull Commented Dec 19, 2016 at 13:47
• 1 The TSLint rule is the bug. Not the code – slebetman Commented Dec 19, 2016 at 13:47
• 3 Wrap it in: /* tslint:disable */ and /* tslint:enable */ (Or be more specific about the rule we are "accepting", see palantir.github.io/tslint/usage/rule-flags ) – Matthew Wilcoxson Commented Dec 19, 2016 at 13:48
• 1 To add a bit of background: The use of bitwise operators is often discouraged in javascript because they can be confused with logical operators. Consider 1 && 1 === 1 and 1 & 1 === 0. – jobB Commented Dec 19, 2016 at 13:54

2 Answers 2

The reason TSLint highlights this is because it is more likely the bitwise operator has been used accidentally (for instance, in an if statement) than to have used it on purpose.

It should be quite acceptable to tell TSLint that you really meant to use a bitwise operator. Just wrap them in special TSLint ments. :

/* tslint:disable:no-bitwise */

// Your code...

/* tslint:enable:no-bitwise */

export abstract class SystemGuid{
    constructor() {
      // no-op
    }
    public static UUID(): string {
      if (typeof window !== 'undefined' && typeof window.crypto !== 'undefined' 
      && typeof window.crypto.getRandomValues !== 'undefined') {
        const buf: Uint16Array = new Uint16Array(8);
        window.crypto.getRandomValues(buf);
        return (
          this.pad4(buf[0]) +
          this.pad4(buf[1]) +
          '-' +
          this.pad4(buf[2]) +
          '-' +
          this.pad4(buf[3]) +
          '-' +
          this.pad4(buf[4]) +
          '-' +
          this.pad4(buf[5]) +
          this.pad4(buf[6]) +
          this.pad4(buf[7])
        );
      } else {
        return (
          this.random4() +
          this.random4() +
          '-' +
          this.random4() +
          '-' +
          this.random4() +
          '-' +
          this.random4() +
          '-' +
          this.random4() +
          this.random4() +
          this.random4()
        );
      }
    }
    private static pad4(num: number): string {
      let ret: string = num.toString(16);
      while (ret.length < 4) {
        ret = '0' + ret;
      }
      return ret;
    }
    private static random4(): string {
      return Math.floor((1 + Math.random()) * 0x10000)
        .toString(16)
        .substring(1);
    }
    public static generate(): string {
      return SystemGuid.UUID();
    }
   }