4 ms·

Why does this use let and var together? Was I (not a modern js expert) wrong to think var is considered obsolete? Is it because OP wanted to use var's scoping r

Why does this use let and var together? Was I (not a modern js expert) wrong to think var is considered obsolete? Is it because OP wanted to use var's scoping rules?

jugg1es 5y ago
var is not obsolete. You still need it sometimes for scoping reasons.
- int_19h 5y ago
  Could you give an example? It seems like any "var" could be replaced with "let" at a different scope.
  - dheera 5y ago
    Won't work: if(checkForSomething()) { let foo = 2; } else { let foo = 3; } console.log(foo); // won't work But: if(checkForSomething()) { var foo = 2; } else { var foo = 3; } console.log(foo); // will work That said, I religiously avoid "var" and just declare the variable beforehand with "let" because there are too many other gotchas with var. Less debugging headaches. And use "const" religiously as well, like C++ people do.
    - speedgoose 5y ago
      const in C++ is very different than const in JavaScript though. I guess you are well aware of that but I feel like being pedantic. This is allowed in JavaScript: const foo = {bar: 1}; foo.bar = 2;
      - int_19h 5y ago
        It's not really any different if you keep in mind that foo is a reference here, and so that's what const applies to. The equivalent in C++ would be a const pointer to a non-const object.
      - zeven7 5y ago
        const foo = Object.freeze({bar: 1});
    - int_19h 5y ago
      That's exactly what I meant by "any "var" could be replaced with "let" at a different scope": let foo; if (checkForSomething()) { foo = 2; } else { foo = 3; }
- zeven7 5y ago
  You don't need var, you don't need it's weird scoping behavior.
yathern 5y ago
It's almost certainly from copy-pasted code from other sources. The Perlin Noise section at the top is not original code at least - though I can't find an original source. https://github.com/processing/p5.js/blob/8213eecccdff510015ef9930ea6ed98584ecdafa/src/math/noise.js https://github.com/processing/p5.js/blob/8213eecccdff510015e...

Why does this use let and var together? Was I (not a modern js expert) wrong to think var is considered obsolete? Is it because OP wanted to use var's scoping rules?

jugg1es 5y ago

var is not obsolete. You still need it sometimes for scoping reasons.

int_19h 5y ago
Could you give an example? It seems like any "var" could be replaced with "let" at a different scope.
- dheera 5y ago
  Won't work: if(checkForSomething()) { let foo = 2; } else { let foo = 3; } console.log(foo); // won't work But: if(checkForSomething()) { var foo = 2; } else { var foo = 3; } console.log(foo); // will work That said, I religiously avoid "var" and just declare the variable beforehand with "let" because there are too many other gotchas with var. Less debugging headaches. And use "const" religiously as well, like C++ people do.
  - speedgoose 5y ago
    const in C++ is very different than const in JavaScript though. I guess you are well aware of that but I feel like being pedantic. This is allowed in JavaScript: const foo = {bar: 1}; foo.bar = 2;
    - int_19h 5y ago
      It's not really any different if you keep in mind that foo is a reference here, and so that's what const applies to. The equivalent in C++ would be a const pointer to a non-const object.
    - zeven7 5y ago
      const foo = Object.freeze({bar: 1});
  - int_19h 5y ago
    That's exactly what I meant by "any "var" could be replaced with "let" at a different scope": let foo; if (checkForSomething()) { foo = 2; } else { foo = 3; }
zeven7 5y ago
You don't need var, you don't need it's weird scoping behavior.

yathern 5y ago

It's almost certainly from copy-pasted code from other sources. The Perlin Noise section at the top is not original code at least - though I can't find an original source. https://github.com/processing/p5.js/blob/8213eecccdff510015ef9930ea6ed98584ecdafa/src/math/noise.js https://github.com/processing/p5.js/blob/8213eecccdff510015e...