js-writer

js-writer

A simple JavaScript object to string converter.

This converts a JavaScript value to a string that is interpretable JavaScript.

Usage

var jsWriter = require('js-writer');

var stringRepresentation = jsWriter({
   a: 42,
   b: 'foo',
   'big-string': `an ES6 string
with line breaks`,
   getMagic: function () { return 42; }
});

console.log(stringRepesentation);


// Output:
// {a:42,b:"foo","big-string":"an ES6 string\nwith line breaks",getMagic:function () { return 42; }}

Custom handling for functions and dates

Passing a handlers object in the options with the (optional) keys of date or function allows you to override the behaviour of these types. The function receives the value, and should return a string of the string representation required.

var s = jsWriter({ f: function foo(a, b) { return a + b; } }, {
  handlers: {
    'function': function (funcValue) {
      return JSON.stringify({ type: 'function', name: funcValue.name });
    }
  }
});

// s == '{f:{"type":"function","name":"foo"}}'

Differences to JSON.stringify

The output is not JSON, it is JavaScript, so object keys that do not need to be quoted aren't, and functions are outputted as interpretable functions (note that normal unbound functions use the native .toString() implementation, so include their source). Dates are recreated by parsing the .toISOString() output (this is done to aid readability, rather than using the native .getTime() value).

Why?

This was developed for use with unexpected-react in order to support snapshot testing with jest and have better matching of functions.

Supported values

Only basic native types are supported (number including NaN, string, undefined, function, Object, Array, Date).

ES6 collection types (Map and Set) are planned, but not yet set when.

License

MIT License

Changelog

v1.1.0

• Add custom handling for functions and dates