for in 和 for ofThe differences and similarities

To compare for in for of
The difference between You can iterate over normal objects

Iterates through the prototype object of the array

You can iterate through the array itself

The value that I’m going to iterate over is 0key

It is not traversablemap/set

You can’t iterategenerators

Internet explorer support		 Normal objects cannot be traversed

It doesn’t iterate through the prototype object

It doesn’t iterate over its own properties

The value that I’m going to iterate over is 0value

Can traversemap/set

To iterategenerators

IE does not support
The same You can iterate through groups of numbers

canbreakInterrupt traversal		 You can iterate through groups of numbers

canbreakInterrupt traversal
  • The sample
const obj = {
    a: 1.b: 2.c: 3.d: 4.e: 5
}
const arr1 = [1.2.3.4.5.6.7.8]
for (let i in obj) {
    console.log('for in break before', i, obj[i])
    if (obj[i] > 3) {
        break
    }
    console.log('for in break after', i, obj[i])
}
console.log('-- -- -- -- -- -)
for (let i of arr1) {
    console.log('for of break before', i)
    if (i > 3) {
        break
    }
    console.log('for of break after', i)
}
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