Question

我试图获取allArrays变量以包含已定义的数组，然后使用该函数在console.log中打印它们。当我尝试这个时，我得到3个具有未定义值的数组，为什么会这样，这将如何工作？

var allArrays = [food, drinks, random];
var food = ["burger","fries","milkshake","sushi"];
var drinks= ["cola","soda","pop"];
var random = ["suck","give","fix me","wooww"];

function selectallArrays (allArrays){
    for (var i =0; i<allArrays.length; i++) {
        console.log(allArrays);
        }
    console.log("--------");
    }

    selectallArrays(allArrays);

Answer 1

您可以更改声明的顺序＆amp;初始化数组，否则将记录undefined。

所有数组都使用var语句声明，并且不会被提升。执行var allArrays = [food, drinks, random];时food，drinks＆amp; random数组未初始化。

var food = ["burger","fries","milkshake","sushi"];
var drinks= ["cola","soda","pop"];
var random = ["suck","give","fix me","wooww"];
var allArrays = [food, drinks, random];

Answer 2

现在应该可以了。

var food = ["burger","fries","milkshake","sushi"];
var drinks= ["cola","soda","pop"];
var random = ["suck","give","fix me","wooww"];
var allArrays = [food, drinks, random];
function selectallArrays (allArrays){
    for (var i =0; i<allArrays.length; i++) {
        console.log(allArrays);
        }
    console.log("--------");
    }

    selectallArrays(allArrays);

Answer 3

这是因为您在定义allArrays，food等其他数组的值之前已在顶部定义了drinks，

在定义其他数组后定义allArrays，

试试这个

var food = ["burger","fries","milkshake","sushi"];
var drinks= ["cola","soda","pop"];
var random = ["suck","give","fix me","wooww"];
var allArrays = [food, drinks, random];

function selectallArrays (allArrays){
    for (var i =0; i<allArrays.length; i++) {
        console.log(allArrays[i]);
        }
    console.log("--------");
    }

    selectallArrays(allArrays);

如何调用在JS中打印多个数组的函数

3 个答案: