react-native-debug-console/packages/lib/src/components/DevTool/Console/tools.js

  var DEFAULT_MAX_DEPTH = 3;
  var DEFAULT_ARRAY_MAX_LENGTH = 50;
  var seen; // Same variable used for all stringifications

  Date.prototype.toPrunedJSON = Date.prototype.toJSON;
  String.prototype.toPrunedJSON = String.prototype.toJSON;

  var cx = /[\u0000\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g,
      escapable = /[\\\"\x00-\x1f\x7f-\x9f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g,
      meta = {    // table of character substitutions
          '\b': '\\b',
          '\t': '\\t',
          '\n': '\\n',
          '\f': '\\f',
          '\r': '\\r',
          '"' : '\\"',
          '\\': '\\\\'
      };

  function quote(string) {
      escapable.lastIndex = 0;
      return escapable.test(string) ? '"' + string.replace(escapable, function (a) {
          var c = meta[a];
          return typeof c === 'string'
              ? c
              : '\\u' + ('0000' + a.charCodeAt(0).toString(16)).slice(-4);
      }) + '"' : '"' + string + '"';
  }

  function str(key, holder, depthDecr, arrayMaxLength) {
      var i,          // The loop counter.
          k,          // The member key.
          v,          // The member value.
          length,
          partial,
          value = holder[key];
      if (value && typeof value === 'object' && typeof value.toPrunedJSON === 'function') {
          value = value.toPrunedJSON(key);
      }

      switch (typeof value) {
      case 'string':
          return quote(value);
      case 'number':
          return isFinite(value) ? String(value) : 'null';
      case 'boolean':
      case 'null':
          return String(value);
      case 'object':
          if (!value) {
              return 'null';
          }
          if (depthDecr<=0 || seen.indexOf(value)!==-1) {
              return '"-pruned-"';
          }
          seen.push(value);
          partial = [];
          if (Object.prototype.toString.apply(value) === '[object Array]') {
              length = Math.min(value.length, arrayMaxLength);
              for (i = 0; i < length; i += 1) {
                  partial[i] = str(i, value, depthDecr-1, arrayMaxLength) || 'null';
              }
              v = partial.length === 0
                  ? '[]'
                  : '[' + partial.join(',') + ']';
              return v;
          }
          for (k in value) {
              if (Object.prototype.hasOwnProperty.call(value, k)) {
                  try {
                      v = str(k, value, depthDecr-1, arrayMaxLength);
                      if (v) partial.push(quote(k) + ':' + v);
                  } catch (e) { 
                      // this try/catch due to some "Accessing selectionEnd on an input element that cannot have a selection." on Chrome
                  }
              }
          }
          v = partial.length === 0
              ? '{}'
              : '{' + partial.join(',') + '}';
          return v;
      }
  }

  export default function (value, depthDecr, arrayMaxLength) {
      seen = [];
      depthDecr = depthDecr || DEFAULT_MAX_DEPTH;
      arrayMaxLength = arrayMaxLength || DEFAULT_ARRAY_MAX_LENGTH;
      const raw = str('', {'': value}, depthDecr, arrayMaxLength);
      // return JSON.stringify(JSON.parse(raw.root), null, '  ');
      return raw;
  };