recursive JSON.stringify implementation

Question

I am trying to learn recursion in Javascript, so I figured I\'d rewrite the native JSON.stringify function using recursion as a challenge to myself. I almost got my

Answer 1

I was asked this in an Interview question and this is what I came up with. An understandable recursive approach:

​
function stringify(input) {
  var arrVals = [];
  Object.keys(input).forEach(function(keyName) {
    let val = input[keyName];
    if (typeof val !== 'undefined' && typeof val !== 'function') {
      arrVals.push(getQuotedString(keyName) + ":" + getString(val));
    }
  });
  return '{' + arrVals.join(',') + '}';
}

function getString(val) {
  switch (typeof val) {
    case 'string':
      return getQuotedString(val);
      break;
    
    case 'number':
    case 'boolean':
      return val;
      break;
    
    case 'object':
      if (val === null) {
        return "null";
      }
      
      if (Array.isArray(val)) {
        let arrString = []
        for (let i = 0; i < val.length; i++) {
          arrString.push(getString(val[i]));
        }
        return "[" + arrString.join(',') + "]";
      }
      
      return stringify(val);
      break;
  }
}

function getQuotedString(str) {
  return '"' + str + '"';
}

Test using following obj:

​
var input = {
  "a": 1,
  "b": 'text',
  "c": {
    "x": 1,
    "y": {
      "x": 2
    }
  },
  "d": false,
  "e": null,
  "f": undefined,
  "g": [1, "text", {
    a: 1,
    b: 2
  }, null]
};