JSON reviver time test created by pranaygp - https://repl.it/@pranaygp/JSON-reviver-time-test

JSON reviver time test.js

const string = JSON.stringify({
  a: 1,
  b: 1,
  c: 1,
  d: 1,
  e: 1,
  f: 1,
  g: 1,
  h: 1,
  a1: 1,
  b1: 1,
  c1: 1,
  d1: 1,
  e1: 1,
  f1: 1,
  g1: 1,
  h1: 1,
  a2: 1,
  b2: 1,
  c2: 1,
  d2: 1,
  e2: 1,
  f2: 1,
  g2: 1,
  h2: 1,
  a3: 1,
  b3: 1,
  c3: 1,
  d3: 1,
  e3: 1,
  f3: 1,
  g3: 1,
  h3: 1,
  a4: 1,
  b4: 1,
  c4: 1,
  d4: 1,
  e4: 1,
  f4: 1,
  g4: 1,
  h4: 1,
  a5: 1,
  b5: 1,
  c5: 1,
  d5: 1,
  e5: 1,
  f5: 1,
  g5: 1,
  h5: 1,
  a6: 1,
  b6: 1,
  c6: 1,
  d6: 1,
  e6: 1,
  f6: 1,
  g6: 1,
  h6: 1,
  a7: 1,
  b7: 1,
  c7: 1,
  d7: 1,
  e7: 1,
  f7: 1,
  g7: 1,
  h7: 1,
})

// setup timing variables
let elapsed = 0
let sTime;


// full parse
for(let i = 0; i < 1e5; i++){
  sTime = process.hrtime();
  
  const obj = JSON.parse(string)
  obj.a;
  
  let diffTime = process.hrtime(sTime)
  elapsed += diffTime[1];
}
console.log(elapsed);

// reset elapsed
elapsed = 0


// partial parse
const reader = (key, val) => {
  if (key === 'a') {
    val;
    
    let diffTime = process.hrtime(sTime)
    elapsed += diffTime[1];
  }
}
for(let i = 0; i < 1e5; i++){
  sTime = process.hrtime();
  
  JSON.parse(string, reader);
}
console.log(elapsed);