own_property_iteration_perf.js

/*
 * Test 1 - for..in with hasOwnProperty check.
 */
var counter = 0
var i
var p
var start = performance.now()
for (i=0; i<1000; i+=1) {
    for (p in window) {
        if (window.hasOwnProperty(p)) {}
    }
}
var end = performance.now()
console.log('Test 1', end - start)

/*
 * Test 2 - for..in with propertyIsEnumerable check.
 */
start = performance.now()
for (i=0; i<1000; i+=1) {
    for (p in window) {
        if (window.propertyIsEnumerable(p)) {}
    }
}
end = performance.now()
console.log('Test 2', end - start)

/*
 * Test 3 - for loop on Object.getOwnPropertyNames
 */
var j
var l
start = performance.now()
var props = Object.getOwnPropertyNames(window)
l = props.length
for (i=0; i<1000; i+=1) {
    for (j=0; j<l; j+=1) {
        if (window.propertyIsEnumerable[props[j]]) {}
    }
}
end = performance.now()
console.log('Test 3', end - start)

/*
 * Test 4 - for loop on Object.keys
 */
start = performance.now()
var props = Object.keys(window)
l = props.length
for (i=0; i<1000; i+=1) {
    for (j=0; j<l; j+=1) {}
}
end = performance.now()
console.log('Test 4', end - start)