Question

我有一个对象数组：

let arr = [{"id":1, "name": "abc"},{"id":2, "name": "fsd"},{"id":3, "name": "fasd"},{"id":4, "name": "fsdfas"},{"id":5, "name": "fad"},{"id":6, "name": "fasdf"},{"id":7, "name": "fasd"},{"id":8, "name": "fasdf"},{"id":9, "name": "fasdfs"},{"id":10, "name": "abc"}]

如何在不使用任何类型的循环语句的情况下检查对象数组中是否存在属性“id”？一旦找到，返回一些字符串或任何东西，例如。

Answer 1

在一般情况下，你不能;某种循环结构是必要的。循环可能在您的代码中，也可能不在您的代码中，但它会在那里。例如，即使您使用数组并通过JSON.stringify运行它然后尝试在结果上使用正则表达式，A）这将是一个坏主意™： - ），并且B）仍然会有循环（在JSON.stringify中，也可能在正则表达式处理中）。而且，开销会比仅仅进行自己的循环要高得多。

如果，在您的情况下，您知道提前该对象都具有相同的属性集，那么您只需检查第一个：

if ("id" in arr[0])

......但是，只有事先知道它们都具有相同的属性。

拉伸一个点，in必须检查对象，如果找不到属性，则必须检查其原型 - 可能包含一个循环。 :-)（当然，任何属性访问都可能必须这样做。）所以你可能更喜欢

if (arr[0].hasOwnProperty("id"))

...理论上，也可能涉及循环通过原型来找到hasOwnProperty方法（实际上，在现代引擎上，它不会）。

Answer 2

您可以使用正则表达式并检查字符串化数组。

＆＃13;

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Answer 3

最接近的是创建一个函数来对数组进行字符串化，然后使用正则表达式查找特定的ID值，如下所示：

正则表达式.test()是（内部）迭代JSON字符串中的字符，因此在基础级别，您要求的是不可能的。

let arr = [{"id":1, "name": "abc"},{"id":2, "name": "fsd"},{"id":3, "name": "fasd"},{"id":4, "name": "fsdfas"},{"id":5, "name": "fad"},{"id":6, "name": "fasdf"},{"id":7, "name": "fasd"},{"id":8, "name": "fasdf"},{"id":9, "name": "fasdfs"},{"id":10, "name": "abc"}];

function idExistsInArray(array, id) {
    var regex = new RegExp("\"id\":" + id + "(,|})");
    return regex.test(JSON.stringify(array));
}

console.log(idExistsInArray(arr, 1));
console.log(idExistsInArray(arr, 3));
console.log(idExistsInArray(arr, 55));

检查对象数组中是否存在属性而不对其进行循环

3 个答案: