Run results for: defineproperty vs direct assignment

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:76.0) Gecko/20100101 Firefox/76.0

Browser: Firefox 76

Operating system: Windows

Device Platform: Desktop

Date tested: 4 years ago

Test name	Executions per second
a	1975.0 Ops/sec
b	37039.4 Ops/sec

Tests:

a

var target = {};
var key = 'something';

for (var i=0; i<1000; i++) {
    target[key+1] = undefined;
}

for (var i=0; i<1000; i++) {
    if (delete target[key+i]) {
        Object.defineProperty(target, key+i, {
          get: function() {return _val;},
          set: function(v) { target._v = v},
        });
    }
}

​x
 
var target = {};var key = 'something';​for (var i=0; i<1000; i++) {    target[key+1] = undefined;}​for (var i=0; i<1000; i++) {    if (delete target[key+i]) {        Object.defineProperty(target, key+i, {          get: function() {return _val;},          set: function(v) { target._v = v},        });    }}

b

var target = {};
var key = 'something';

for (var i=0; i<1000; i++) {
    target[key+1] = undefined;
}

 
var target = {};var key = 'something';​for (var i=0; i<1000; i++) {    target[key+1] = undefined;}