InternedStrings

InternedString.js

// Class
class InternedString {
  static internedStrings = new Map();
  static nextId = 0;

  constructor(value) {
    this.id = InternedString.nextId++;
    this.value = value;
  }

  static intern(value) {
    if (InternedString.internedStrings.has(value)) {
      return InternedString.internedStrings.get(value);
    }

    const internedString = new InternedString(value);
    InternedString.internedStrings.set(value, internedString);
    return internedString;
  }

  equals(other) {
    return other === this.value;
  }

  copy() {
    return this.value;
  }

  toString() {
    return this.value;
  }
}

InternedStringBenchmark.js

const numIterations = 100000;
const str = 'hello';

function benchmarkInternedString() {
  const internedStr = InternedString.intern(str);
  let start = Date.now();
  for (let i = 0; i < numIterations; i++) {
    internedStr.equals(str);
  }
  console.log(`InternedString equality: ${Date.now() - start}ms`);
}

function benchmarkInternedStringCopy() {
  const internedStr = InternedString.intern(str);
  let start = Date.now();
  for (let i = 0; i < numIterations; i++) {
    internedStr.copy();
  }
  console.log(`InternedString copy: ${Date.now() - start}ms`);
}

benchmarkInternedString();
benchmarkInternedStringCopy();

NativeStringBenchmark.js

const numIterations = 100000;
const str = 'hello';

function benchmarkNativeString() {
  let start = Date.now();
  for (let i = 0; i < numIterations; i++) {
    str === str;
  }
  console.log(`NativeString equality: ${Date.now() - start}ms`);
}

function benchmarkNativeStringCopy() {
  let start = Date.now();
  for (let i = 0; i < numIterations; i++) {
    str + '';
  }
  console.log(`NativeString copy: ${Date.now() - start}ms`);
}

benchmarkNativeString();
benchmarkNativeStringCopy();