Are there limits to the number of properties in a JavaScript object?

From our test on this issue it seems that IE9, Windows 7, limits the number of line in a HTA script to 65535. I did not find any source on the issue, it is just the results of our tests.

The exact maximum limit of an array is 2^32 - 1 or 4294967295, due to restrictions in Javascript's memory.

Link

I'm not sure what the actual value is, but I see the practical upper limit around 400,000 in node.js (on a Mac with 16 GB of RAM).

Here is a log of me adding rows from a database into an object:

[[21:32:34.325]] [LOG] 340001, pint of delight
[[21:32:35.574]] [LOG] 350001, pound shrimp
[[21:32:36.545]] [LOG] 360001, ravioli allaragosta
[[21:32:37.721]] [LOG] 370001, roasted ham and cheese
[[21:32:39.862]] [LOG] 380001, salmon kama
[[21:32:41.152]] [LOG] 390001, scallops and vegetables
[[21:32:42.150]] [LOG] 400001, show cabernet ca
[[21:32:44.412]] [LOG] 410001, sloppy nachos
[[21:33:25.425]] [LOG] 420001, spaghetti or ziti sauce
[[21:35:37.839]] [LOG] 430001, steak au poivre vert
[[21:37:37.202]] [LOG] 440001, sushi moriawase
[[21:39:45.365]] [LOG] 450001, tequila shooters
[[21:42:09.036]] [LOG] 460001, toro roll with scallion
[[21:44:32.796]] [LOG] 470001, two enchiladas taco rice and refried beans
[[21:47:02.584]] [LOG] 480001, veuve clicquot ponsardin rose reims nv
[[21:49:04.020]] [LOG] 490001, whole turkey gourmet sides
[[21:51:15.264]] [LOG] finished

Until around 400,000 it takes about 1 second to insert 10,000 new records. Past 410,000, the time increases almost exponentially.

I'm not sure how I'll solve this. Maybe make 2 objects and limit them to 400,000 keys each... a bit labor-intensive but better than rewriting a dictionary object :)

Update: It looks like it's actually the amount of memory used that is the issue and not so much the number of objects. My machine slows to a crawl at about 1.5 GB of RAM used. It might be linked to the memory allocated to the node.js process, which can be increased with this parameter: --max_old_space_size=4096 (number is in MB).

In the current version of Chrome (Sept 2017), I'm limited to around 8.3 million keys. Try pasting this in your browser console:

let obj = {};
let keyCount = 0;
while(1) {
  obj[Math.random()] = Math.random();
  if(++keyCount % 10000 === 0) console.log(keyCount);
}

I get an identical limit in Node.js:

node --max-old-space-size=20000 -e "let obj = {}; let keyCount = 0; while(1) { obj[Math.random()] = Math.random(); if(++keyCount % 10000 === 0) console.log(keyCount); }"

Interestingly, if I use a Map, I can get about 16.8 million keys before it crashes (you can get past this limit with something like this).