First fundamentals. V8 uses hidden classes connected with transitions to discover static structure in the fluffy shapeless JavaScript objects. Hidden classes describe the structure of the object, transitions link hidden classes together describing which hidden class should be used if a certain action is performed on an object. For example the code below would lead … Read more
Yes. In general any literal string, identifier, or other constant string in JS source is interned. However implementation details (exactly what is interned for instance) varies, as well as when the interning occurs. Note that a string value is not the same as a String Object though, String Objects are not interned because that would … Read more
The problem is not with the Javascript math; it’s with the canvas. http://jsfiddle.net/LDWBX/ function bigCircle(angle) { var radius = 5000; //the bigger, the worse var x = canvas.width/2 + radius*Math.cos(angle); var y = canvas.height/2 + radius*Math.sin(angle); ctx.beginPath(); ctx.arc(x, y, radius, 0, 2 * Math.PI); ctx.lineWidth = 2; ctx.stroke(); } Notice that numbers appear exactly the … Read more
This is what I use: var escapeShell = function(cmd) { return ‘”‘+cmd.replace(/([“‘$`\\])/g,’\\$1’)+'”‘; };
I’m sure the following is a simplification, but it works for me. An isolate is an independent copy of the V8 runtime, including a heap manager, a garbage collector, etc. Only one thread may access a given isolate at a time, but different threads may access different isolates simultaneously. An isolate is not sufficient for … Read more
You should always run untrusted code in a separate process, which is exactly what the sandbox module does. A simple reason is that vm.runInNewContext(‘while(true){}’, {}) will freeze node. It starts by spawning a separate process, which will later send the result serialized to JSON on its stdout. The parent process continues executing regardless of what … Read more
The DOM is the DOM, and the JavaScript implementation is simply a separate entity. The DOM represents a set of facilities that a web browser exposes to the JavaScript environment. There’s no requirement however that any particular JavaScript runtime will have any facilities exposed via the global object. What Node.js is is a stand-alone JavaScript … Read more
Since NodeJS v12 async stack traces are enabled by default. relevant issue how async stacktraces work
You can use either of these functions: // This should work in node.js and other ES5 compliant implementations. function isEmptyObject(obj) { return !Object.keys(obj).length; } // This should work both there and elsewhere. function isEmptyObject(obj) { for (var key in obj) { if (Object.prototype.hasOwnProperty.call(obj, key)) { return false; } } return true; } Example usage: if … Read more
V8 developer here. It’s not a bug, it’s just an optimization that V8 doesn’t do. It’s interesting to see that Firefox seems to do it… FWIW, I don’t see “ballooning to 400ms”; instead (similar to Jon Trent’s comment) I see about 2.5ms at first, and then around 11ms. Here’s the explanation: When you click only … Read more