Correct bad Date.prototype.toJSON polyfills from elsewhere

[petermichaux]

Douglas Crockford's json2.js, for example, defines a Date.prototype.toJSON function that does not pad extended years with zeros as the es5-shim does in Date.prototype.toISOString does.

es5-shim can redefine a bad Date.prototype.toJSON by changing

if (!Date.prototype.toJSON) {

to

if (!Date.prototype.toJSON ||
    (new Date(-62198755200000).toJSON().indexOf('-000001') === -1)) {

This also means people using json2.js need to include json2.js in their environment before including es5-shim as defining Date.prototype.toJSON means other things will not be defined in json2.js

[petermichaux]

json2.js Date.prototoype.toJSON is also not generic. If json2.js is updated to handle extended dates correctly but not to be generic then the following check would fix things.

if (!Date.prototype.toJSON ||
    // does Date.prototype.toJSON not do extended years properly?
    ((new Date(-62198755200000)).toJSON().indexOf('-000001') === -1) ||
    // is Date.prototype.toJSON non-generic?
    (function() {
        var str = 'abc';
        try {
            return Date.prototype.toJSON.call({toISOString:function(){return str;}}) !== str;
        }
        catch (err) {
            return true;
        }
    }())) {

[kriskowal]

Thanks, @petermichaux. Good to cross paths again!

[petermichaux]

I admit the above feature test is ugly.

A workaround that could be documented in the README?...

<script src="json2.js" type="text/javascript"></script>
<script type="text/javascript">
    delete Date.prototype.toJSON
</script>
<script src="es5-shim.js" type="text/javascript"></script>

[petermichaux]

By the way, Crockford closed my tickets about improving the Date.prototype.toJSON in his json2.js.

[bryanforbes]

What about something like this?

if (!Date.prototype.toJSON ||
    // does Date.prototype.toJSON not do extended years properly?
    !~((new Date(-62198755200000)).toJSON().indexOf('-000001')) ||
    // is Date.prototype.toJSON non-generic?
    ~(function() {
        try {
            return Date.prototype.toJSON.call({toISOString:function(){return -1;}});
        } catch (err) {
            return true;
        }
    }())) {

[jdalton]

Relevant:
douglascrockford/JSON-js#27
douglascrockford/JSON-js#25

[jdalton]

Additional json2.js issues:
douglascrockford/JSON-js#28