Improve JavaScript performance in V8

array.js

a = new Array();
for (var b = 0; b < 10; b++) {
    a[0] |= b;
}


a = new Array();
a[0] = 0; // just this change alone make code 2x faster
for (var b = 0; b < 10; b++) {
    a[0] |= b;
}

classes.js

function Point(x,y) {
    this.x = x;
    this.y - y;
}

var p1 = new Point(11, 22);
var p2 = new Point(15, 42);
p2.z = 15; // don't do this

v8-commands.sh

# log names of optimized functions
d8 --trace-opt primes.js

# logs optimizing compiler bailouts
d8 --trace-bailout prmies.js

# log functions that v8 had to deoptimize
d8 --trace-deopt primes.js

# You can also call Chrome with all flags
"/Applications/Google Chrome/MacOs/Google Chrome" --js-flags = "--trace-opt --trace-deopt --trace-bailout"

thank you 👍