index.js

'use strict';
const isRegexp = require('is-regexp');
const isObj = require('is-obj');
const getOwnEnumPropSymbols = require('get-own-enumerable-property-symbols');

module.exports = (val, opts, pad) => {
	const seen = [];

	return (function stringify(val, opts, pad) {
		opts = opts || {};
		opts.indent = opts.indent || '\t';
		pad = pad || '';

		let tokens;

		if (opts.inlineCharacterLimit === undefined) {
			tokens = {
				newLine: '\n',
				newLineOrSpace: '\n',
				pad,
				indent: pad + opts.indent
			};
		} else {
			tokens = {
				newLine: '@@__STRINGIFY_OBJECT_NEW_LINE__@@',
				newLineOrSpace: '@@__STRINGIFY_OBJECT_NEW_LINE_OR_SPACE__@@',
				pad: '@@__STRINGIFY_OBJECT_PAD__@@',
				indent: '@@__STRINGIFY_OBJECT_INDENT__@@'
			};
		}

		const expandWhiteSpace = string => {
			if (opts.inlineCharacterLimit === undefined) {
				return string;
			}

			const oneLined = string
				.replace(new RegExp(tokens.newLine, 'g'), '')
				.replace(new RegExp(tokens.newLineOrSpace, 'g'), ' ')
				.replace(new RegExp(tokens.pad + '|' + tokens.indent, 'g'), '');

			if (oneLined.length <= opts.inlineCharacterLimit) {
				return oneLined;
			}

			return string
				.replace(new RegExp(tokens.newLine + '|' + tokens.newLineOrSpace, 'g'), '\n')
				.replace(new RegExp(tokens.pad, 'g'), pad)
				.replace(new RegExp(tokens.indent, 'g'), pad + opts.indent);
		};

		if (seen.indexOf(val) !== -1) {
			return '"[Circular]"';
		}

		if (val === null ||
			val === undefined ||
			typeof val === 'number' ||
			typeof val === 'boolean' ||
			typeof val === 'function' ||
			typeof val === 'symbol' ||
			isRegexp(val)) {
			return String(val);
		}

		if (val instanceof Date) {
			return `new Date('${val.toISOString()}')`;
		}

		if (Array.isArray(val)) {
			if (val.length === 0) {
				return '[]';
			}

			seen.push(val);

			const ret = '[' + tokens.newLine + val.map((el, i) => {
				const eol = val.length - 1 === i ? tokens.newLine : ',' + tokens.newLineOrSpace;
				return tokens.indent + stringify(el, opts, pad + opts.indent) + eol;
			}).join('') + tokens.pad + ']';

			seen.pop(val);

			return expandWhiteSpace(ret);
		}

		if (isObj(val)) {
			const objKeys = Object.keys(val).concat(getOwnEnumPropSymbols(val));

			if (objKeys.length === 0) {
				return '{}';
			}

			seen.push(val);

			const ret = '{' + tokens.newLine + objKeys.map((el, i) => {
				if (opts.filter && !opts.filter(val, el)) {
					return '';
				}

				const eol = objKeys.length - 1 === i ? tokens.newLine : ',' + tokens.newLineOrSpace;
				const isSymbol = typeof el === 'symbol';
				const isClassic = !isSymbol && /^[a-z$_][a-z$_0-9]*$/i.test(el);
				const key = isSymbol || isClassic ? el : stringify(el, opts);
				return tokens.indent + String(key) + ': ' + stringify(val[el], opts, pad + opts.indent) + eol;
			}).join('') + tokens.pad + '}';

			seen.pop(val);

			return expandWhiteSpace(ret);
		}

		if (opts.joinLines !== false) {
			val = String(val).replace(/[\r\n]/g, x => x === '\n' ? '\\n' : '\\r');
		}

		if (opts.singleQuotes === false) {
			val = val.replace(/"/g, '\\"');
			return `"${val}"`;
		}

		val = val.replace(/'/g, '\\\'');
		return `'${val}'`;
	})(val, opts, pad);
};