发现个关于for in的问题，想请教下

[senlin-wei]

源码（对象第一个属性不同）：
var obj = {a: 1, b: 2, c: 3, d: 4, e: 5, '-': 6};
var objN = {1: 1, b: 2, c: 3, d: 4, e: 5, '-': 6};
suite
.add('for .. in ..:', function () {
for (var k in obj) {
obj[k]
}
})
.add('for .. in N :', function () {
for (var k in objN) {
obj[k]
}
})
.on('cycle', function(event) {
console.log(String(event.target));
})
.on('complete', function() {
console.log('Fastest is ' + this.filter('fastest').map('name'));
})
// run async
.run({ 'async': true });

结果：
for .. in ..: x 12,439,181 ops/sec ±5.58% (75 runs sampled)
for .. in N : x 870,694 ops/sec ±6.75% (70 runs sampled)
Fastest is for .. in ..:
为什么用数字作为key，效率会这么低呢

[alsotang]

真不知道。。

2016-07-11 17:31 GMT+08:00 senlin-wei [email protected]:

源码（对象第一个属性不同）：
var obj = {a: 1, b: 2, c: 3, d: 4, e: 5, '-': 6};
var objN = {1: 1, b: 2, c: 3, d: 4, e: 5, '-': 6};
suite
.add('for .. in ..:', function () {
for (var k in obj) {
obj[k]
}
})
.add('for .. in N :', function () {
for (var k in objN) {
obj[k]
}
})
.on('cycle', function(event) {
console.log(String(event.target));
})
.on('complete', function() {
console.log('Fastest is ' + this.filter('fastest').map('name'));
})
// run async
.run({ 'async': true });

结果：
for .. in ..: x 12,439,181 ops/sec ±5.58% (75 runs sampled)
for .. in N : x 870,694 ops/sec ±6.75% (70 runs sampled)
Fastest is for .. in ..:
为什么用数字作为key，效率会这么低呢

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