[@turf/clone] - object with key "length" is interpreted as array due to value.length in js code

[udos]

I have a GeoJSON feature with a key "length":

myGeoJSON = {
    geometry: [...],
    bbox: [...],
    properties: {
        processed: {
            length: {
                orig: 123.456,
                opti: 100.00,
            },
        }
    }
};

at some point, clone is called, which interprets the processed object as an array due to line

} else if (value.length) {

in

/**
 * Clone Properties
 *
 * @private
 * @param {Object} properties GeoJSON Properties
 * @returns {Object} cloned Properties
 */
function cloneProperties(properties) {
    var cloned = {};
    if (!properties) return cloned;
    Object.keys(properties).forEach(function (key) {
        var value = properties[key];
        if (typeof value === 'object') {
            if (value === null) {
                // handle null
                cloned[key] = null;
            } else if (value.length) {
                // handle Array
                cloned[key] = value.map(function (item) {
                    return item;
                });
            } else {
                // handle generic Object
                cloned[key] = cloneProperties(value);
            }
        } else cloned[key] = value;
    });
    return cloned;
}

and throws an error...

looking at the TypeScript code, it looks as this is handled properly (source: https://github.com/Turfjs/turf/blob/master/packages/turf-clone/index.ts#L78):

} else if (Array.isArray(value)) {

there might be a reason for this, but it would be nice if JS array identification would be done in a more robust way.

p.s.: meanwhile I change my key :|

[rowanwins]

Thanks for the report @udos

[rowanwins]

I've just done a quick check and I'm having trouble replicating your error
https://runkit.com/rowanwins/clone-issue

Another option to check out is the v5 series of modules was published using regular js so there shouldn't be any ts to js transformation issues there.

Hope that helps

[udos]

@rowanwins, I tried to reproduce on runkit but I'm struggling to understand how to use it properly :|

is it possible that nodejs is using the ts files where the Array identification is properly identified?

note: I'm using the latest versions via npm. actually I'm using @turf/simplify which at some point calls @turf/clone when the error is thrown.

from your runkit I noticed that @turf/clone is at version 6.0.2. @turf/simplify is at version 5.1.5. @turf/clone is a dependency of @turf/simplify (package-lock.json):

"@turf/simplify": {
      "version": "5.1.5",
      "resolved": "https://registry.npmjs.org/@turf/simplify/-/simplify-5.1.5.tgz",
      "integrity": "sha1-Csjyei60IYGD7dmZjDJ1q+QIuSY=",
      "requires": {
        "@turf/clean-coords": "^5.1.5",
        "@turf/clone": "^5.1.5",
        "@turf/helpers": "^5.1.5",
        "@turf/meta": "^5.1.5"

so @turf/clone is "locked" at version 5.5. I will try to re-install @turf/simplify to see if this changes.
npm outdated did not indicate me outdated turf components...

[rowanwins]

As yes ok with v@5.1.5 of clone I'm seeing the issue, looks like the offending code is here . It looks like it was resolved last year in the v6 series here.

The challenge you'll have is that @turf/simplify hasn't been re-released at a v6 module which means the changes to clone haven't been incorporated :(

[udos]

thanks. no worries!

the workaround until @turf/simplify is re-released as a v6 module could be that I uninstall @turf/simplify, install @turf/clone 6.0.2 (so it is available as a package and not as a dependency) and then re-install @turf/simplify. @turf/simplify might then use @turf/clone 6.0.2...

I will give that a try later today

[smallsaucepan]

Fairly sure this would have been resolved when Turf updated its JS target from es5 (as of v5.1.5) to es20xx. Have confirmed the currently generated code for CJS and ESM builds uses the Array.isArray call rather than the value.length check.

Have submitted PR #2749 to add a regression test making sure a property with a name length makes it through cloning unscathed.