如果该对象表示的类或接口未实现接口，方法返回的数组长度为0。

If this object represents a class or interface that implements no interfaces, the method returns an array of length 0.

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此配额控制由各种 API 调用创建和返回的最大数组长度。

This quota governs the maximum array length that is created and returned by various API calls.

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在数组开始位置添加一个或多个元素并返回新的数组长度。

Unshift adds one or more elements to the beginning of an array and returns the new length of the array.

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