While your method does generate a somewhat random string that could be used as a UUID, it sacrifices readability for brevity and doesn't adhere to RFC standards for UUIDs. For an improved version of your function, refer to: . To delve further into UUID details, visit:
Let's now concentrate on the line in question and break down its components.
var r = Math.random() * 16 | 0, v = c == 'x' ? r : (r & 0x3 | 0x8);
This single line declares two variables: r and v, which can easily be split into two separate lines.
var r = Math.random() * 16 | 0;
var v = c == 'x' ? r : (r & 0x3 | 0x8);
Variable Definition 1: (r = Math.random() * 16 | 0;):
Math.random() outputs a value between 0 and 1 (inclusive of 0, exclusive of 1).- Multiplying the result by 16 yields a range from
0 to 16 (inclusive of 0, exclusive of 16).
- The bitwise OR operation with zero (
| 0) effectively rounds down the number to an integer within the range of 0 to 15 (inclusive).
- To enhance clarity, you can replace this floor operation with
Math.floor(Math.random() * 16) instead of using a bitwise operation shortcut.
All bitwise operations except unsigned right shift, >>>, work on
signed 32-bit integers. So using bitwise operations will convert a
float to an integer.
var r = Math.floor(Math.random() * 16);
Variable Definition 2 (var v = c == 'x' ? r : (r & 0x3 | 0x8);
):
- This line employs a ternary operator for concise assignment syntax based on a condition.
- The ternary statement can be restructured using a traditional
if/else block for improved readability.
Variable Definition 2.1 (var v = r & 0x3 | 0x8):
- Given that
r ranges from 0 to 15 inclusively...
- By applying the AND operation with
0x3 and the subsequent OR operation with 0x8, v ends up with values of 8, 9, 10, or 11.
- Note: This scenario won't actually occur in your implementation since the string manipulation only involves replacing
x characters.
For detailed insights into bitwise operations, visit: https://www.w3schools.com/js/js_bitwise.asp
tldr: Provide a TypeScript method for generating a UUID.
Referencing @broofa's latest iteration ():
uuidv4(): string {
// @ts-ignore
return ([1e7] + -1e3 + -4e3 + -8e3 + -1e11).replace(/[018]/g, c =>
// tslint:disable-next-line:no-bitwise
(c ^ crypto.getRandomValues(new Uint8Array(1))[0] & 15 >> c / 4).toString(16)
);
}
As a reference point: simplifying your approach into TypeScript:
generateUniqSerial(): string {
return 'xxxx-xxxx-xxx-xxxx'.replace(/[x]/g, (c) => {
const r = Math.floor(Math.random() * 16);
return r.toString(16);
});
}