javascript - 使用javascript计算数组数组的长度

Question

我有这个数组，我想计算其中的总数，谁能告诉我如何使用纯 javascript 实现这个

var total = {
    "numbers":{
        "1":"9897877884",
        "2":"9867543234",
        "3":"7898879900",
        "4":"1234567890"
    }
}

Answer 1

您可以使用 Object.keys(total.numbers).length。第一部分返回一个包含键的数组，第二部分获取它的长度。

var total = { "numbers": { "1": "9897877884", "2": "9867543234", "3": "7898879900", "4": "1234567890" } };
console.log(Object.keys(total.numbers).length);

Object.keys()

The Object.keys() method returns an array of a given object's own enumerable properties, in the same order as that provided by a for...in loop (the difference being that a for-in loop enumerates properties in the prototype chain as well).

Array#length

The length property represents an unsigned, 32-bit integer that is always numerically greater than the highest index in the array.