refactor: dont covert to charcode in iswhitespace

[SethFalco]

While looking through path.js, I noticed we had a isWsp function, which wasn't immediately obvious was an abbreviation for isWhiteSpace. So I renamed it to isWhiteSpace so it's obvious what it's doing.

From there, since we're stepping through a string char by char before calling the function, it's redundant to call codePointAt when we can just compare the string immediately. This is both faster and more readable for maintainers.

Finally, I just apply a proposal from SonarLint to replace an else { if () } with else if ().

Benchmark

const Benchmark = require('benchmark');
const suite = new Benchmark.Suite;

const data = [
  '0', // false
  '1', // false
  '-', // false
  '.', // false
  ' ', // true
  '\t', // true
  '\n', // true
  '\r', // true
  ' ', // false (technically true, but we didn't accept it before so false)
]

const isWhiteSpaceV1 = (c) => {
  const codePoint = c.codePointAt(0);
  return (
    codePoint === 0x20 ||
    codePoint === 0x9 ||
    codePoint === 0xd ||
    codePoint === 0xa
  );
};

const isWhiteSpaceV2 = (c) => {
  return (
    c === ' ' ||
    c === '\t' ||
    c === '\r' ||
    c === '\n'
  );
};

const set = new Set([' ', '\t', '\r', '\n']);
const isWhiteSpaceV3 = (c) => {
  return set.has(c);
};

suite.add('v1', () => {
  data.map((d) => isWhiteSpaceV1(d));
})
.add('v2', () => {
  data.map((d) => isWhiteSpaceV2(d));
})
.add('v3', () => {
  data.map((d) => isWhiteSpaceV3(d));
})
.on('cycle', (event) => {
  console.log(String(event.target));
})
.on('complete', function() {
  console.log('Fastest is ' + this.filter('fastest').map('name'));
})
.run({ 'async': true });

v1 x 28,871,343 ops/sec ±0.98% (86 runs sampled)
v2 x 50,999,166 ops/sec ±1.33% (90 runs sampled)
v3 x 15,390,647 ops/sec ±0.76% (96 runs sampled)
Fastest is v2

The impact of this change on our regression tests is negligible and within margin of error, but the code is cleaner imo, so I'm running with it.

Previous runs from other pull requests:

• 16 minutes 57 seconds
• 20 minutes 33 seconds
• 16 minutes 46 seconds
• 16 minutes 59 seconds

This run: 16 minutes 43 seconds