JavaScript中Array()函数是什么？如何查找其官方技术文档？

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1. What exactly is the Array() function with a numeric parameter? #

The Array() is a built-in JavaScript constructor function for creating array objects. When you pass a single non-negative integer to it (like Array(10)), it creates an array with its length property set to that number—but crucially, the array doesn’t hold actual values; it contains empty slots (often called "holes" in array terminology).

For example:

const emptyLengthArr = Array(10);
console.log(emptyLengthArr.length); // Logs 10
console.log(emptyLengthArr[0]); // Logs undefined (since the slot is empty)

This is why you pair it with Array.from(Array(10).keys()) to get a filled numeric array:

• Array(10).keys() returns an iterator that yields the array’s indices (0 through 9, matching the array’s length)
• Array.from() converts that iterator into a proper array with actual numeric values, resulting in [0, 1, 2, ..., 9]

A quick side note: If you pass multiple arguments to Array() (like Array(1, 2, 3)), it behaves differently—it creates an array containing those exact values instead of just setting a length.

2. Where to find the official documentation? #

The definitive official documentation for the Array() constructor lives in the MDN Web Docs JavaScript reference. Look for the "Array constructor" section, which covers every detail: how it handles numeric parameters, multiple arguments, edge cases (like non-integer or negative values), and related methods to work with arrays.

内容的提问来源于stack exchange，提问作者arcmeme