json-beautify/index.js

JSON.stringify with fixed maximum character width.

var rx_escapable = /[\\\"\u0000-\u001f\u007f-\u009f\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g;

var gap,
    indent,
    meta = { // table of character substitutions
      '\b': '\\b',
      '\t': '\\t',
      '\n': '\\n',
      '\f': '\\f',
      '\r': '\\r',
      '"': '\\"',
      '\\': '\\\\'
    },
    rep;

function quote(string) {

// If the string contains no control characters, no quote characters, and no
// backslash characters, then we can safely slap some quotes around it.
// Otherwise we must also replace the offending characters with safe escape
// sequences.

    rx_escapable.lastIndex = 0;
    return rx_escapable.test(string)
        ? '"' + string.replace(rx_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, limit) {

// Produce a string from holder[key].

    var i,          // The loop counter.
        k,          // The member key.
        v,          // The member value.
        length,
        mind = gap,
        partial,
        value = holder[key];

// If the value has a toJSON method, call it to obtain a replacement value.

    if (value && typeof value === 'object' &&
            typeof value.toJSON === 'function') {
        value = value.toJSON(key);
    }

// If we were called with a replacer function, then call the replacer to
// obtain a replacement value.

    if (typeof rep === 'function') {
        value = rep.call(holder, key, value);
    }

// What happens next depends on the value's type.

    switch (typeof value) {
    case 'string':
        return quote(value);

    case 'number':

// JSON numbers must be finite. Encode non-finite numbers as null.

        return isFinite(value)
            ? String(value)
            : 'null';

    case 'boolean':
    case 'null':

// If the value is a boolean or null, convert it to a string. Note:
// typeof null does not produce 'null'. The case is included here in
// the remote chance that this gets fixed someday.

        return String(value);

// If the type is 'object', we might be dealing with an object or an array or
// null.

    case 'object':

// Due to a specification blunder in ECMAScript, typeof null is 'object',
// so watch out for that case.

        if (!value) {
            return 'null';
        }

// Make an array to hold the partial results of stringifying this object value.

        gap += indent;
        partial = [];

// Is the value an array?

        if (Object.prototype.toString.apply(value) === '[object Array]') {

// The value is an array. Stringify every element. Use null as a placeholder
// for non-JSON values.

            length = value.length;
            for (i = 0; i < length; i += 1) {
                partial[i] = str(i, value, limit) || 'null';
            }

// Join all of the elements together, separated with commas, and wrap them in
// brackets.

            v = partial.length === 0
                ? '[]'
                : gap
                    ? (
                      gap.length + partial.join(', ').length + 4 > limit ?
                      '[\n' + gap + partial.join(',\n' + gap) + '\n' + mind + ']' :
                      '[ ' + partial.join(', ') + ' ]'
                    )
                    : '[' + partial.join(',') + ']';
            gap = mind;
            return v;
        }

// If the replacer is an array, use it to select the members to be stringified.

        if (rep && typeof rep === 'object') {
            length = rep.length;
            for (i = 0; i < length; i += 1) {
                if (typeof rep[i] === 'string') {
                    k = rep[i];
                    v = str(k, value, limit);
                    if (v) {
                        partial.push(quote(k) + (
                            gap
                                ? ': '
                                : ':'
                        ) + v);
                    }
                }
            }
        } else {

// Otherwise, iterate through all of the keys in the object.

            for (k in value) {
                if (Object.prototype.hasOwnProperty.call(value, k)) {
                    v = str(k, value, limit);
                    if (v) {
                        partial.push(quote(k) + (
                            gap
                                ? ': '
                                : ':'
                        ) + v);
                    }
                }
            }
        }

// Join all of the member texts together, separated with commas,
// and wrap them in braces.

        v = partial.length === 0
            ? '{}'
            : gap
                ? (
                  gap.length + partial.join(', ').length + 4 > limit ?
                  '{\n' + gap + partial.join(',\n' + gap) + '\n' + mind + '}' :
                  '{ ' + partial.join(', ') + ' }'
                )
                : '{' + partial.join(',') + '}';
        gap = mind;
        return v;
    }
}


function beautify (value, replacer, space, limit) {

// The stringify method takes a value and an optional replacer, and an optional
// space parameter, and returns a JSON text. The replacer can be a function
// that can replace values, or an array of strings that will select the keys.
// A default replacer method can be provided. Use of the space parameter can
// produce text that is more easily readable.

  var i;
  gap = '';
  indent = '';

  if (!limit) limit = 0;

  if (typeof limit !== "number")
    throw new Error("beaufifier: limit must be a number");

// If the space parameter is a number, make an indent string containing that
// many spaces.

  if (typeof space === 'number') {
      for (i = 0; i < space; i += 1) {
          indent += ' ';
      }

// If the space parameter is a string, it will be used as the indent string.

  } else if (typeof space === 'string') {
      indent = space;
  }

// If there is a replacer, it must be a function or an array.
// Otherwise, throw an error.

  rep = replacer;
  if (replacer && typeof replacer !== 'function' &&
          (typeof replacer !== 'object' ||
          typeof replacer.length !== 'number')) {
      throw new Error('beautifier: wrong replacer parameter');
  }

// Make a fake root object containing our value under the key of ''.
// Return the result of stringifying the value.

  return str('', {'': value}, limit);
}

module.exports = beautify;