javascript - 如何在 JavaScript 中构建循环？

Question

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Answer 1

For 循环

for (i = startValue; i <= endValue; i++) {
    // Before the loop: i is set to startValue
    // After each iteration of the loop: i++ is executed
    // The loop continues as long as i <= endValue is true
}

For...in 循环

for (i in things) {
    // If things is an array, i will usually contain the array keys *not advised*
    // If things is an object, i will contain the member names
    // Either way, access values using: things[i]
}

使用 for...in 循环遍历数组是不好的做法。它违背了 ECMA 262标准，并且在将非标准属性或方法添加到 Array 对象时可能会导致问题，例如通过 Prototype . (感谢 Chase Seibert 在评论中指出这一点)

While 循环

while (myCondition) {
    // The loop will continue until myCondition is false
}