Pretty print JavaScript objects (does not conform to JSON, because we don't want escape sequences in string literals)

prettyprint.js

function isPlainObject(o) {
  return o && toString.call(o) === '[object Object]' && 'isPrototypeOf' in o;
}

function isArray(o) {
  return toString.call(o) == '[object Array]';
}

function objectToString(val) {
  var INDENT = '  ';
  
  var lines = [];
  _objectToString(val, 0, lines);
  return lines.join('<br />');
  
  function _makeIndent(nestDepth) {
    var indent = '';
    for (var i = 0; i < nestDepth; i++) {
      indent += INDENT;
    }
    return indent;
  }

  function _makeLine(val, nestDepth, propName) {
    var indent = _makeIndent(nestDepth);
    propName = propName && propName + ': ' || '';
    return indent + propName + val;
  }

  function _objectToString(val, nestDepth, lines, propName) {
    var indent = _makeIndent(nestDepth);
    
    if (isPlainObject(val)) {
      lines.push(indent + '{');
      for (var prop in val) {
        _objectToString(val[prop], nestDepth + 1, lines, prop);
      }
      lines.push(indent + '}');
    } else if (isArray(val)) {
      lines.push(indent + '[');
      for (var i = 0; i < val.length; i++) {
        _objectToString(val[i], nestDepth + 1, lines);
      }
      lines.push(indent + ']');
    } else {
      lines.push(_makeLine(val, nestDepth, propName));
    }
  }
}