使用值(Javascript)返回数组
如果您只知道数组的一个值,是否可以获取该数组 我有两个数组,想找出哪个数组有变量:使用值(Javascript)返回数组,javascript,arrays,Javascript,Arrays,如果您只知道数组的一个值,是否可以获取该数组 我有两个数组,想找出哪个数组有变量: var fruit = ["apple","banana","orange"]; var veggie = ["carrot","pea","corn"]; alert("An apple is a " + /*return array with value "apple"*/); 可以用Javascript实现这一点吗?谢谢将警报包装在if/else语句中,并检查“apple”索引。如果fruit.index
var fruit = ["apple","banana","orange"];
var veggie = ["carrot","pea","corn"];
alert("An apple is a " + /*return array with value "apple"*/);
可以用Javascript实现这一点吗?谢谢将警报包装在if/else语句中,并检查“apple”索引。如果
fruit.indexOf('apple')!=-1
那么它必须是一个水果。您可以使用如下函数,并在每个相关数组上调用它:
function contains(a, obj) { //a is the array to check, and obj the object you are looking for
var i = a.length;
while (i--) {
if (a[i] === obj) {
return true;
}
}
return false;
}
我将使用一个对象来包含各种类型:
var type = {
fruit: ["apple", "banana", "orange"],
veggie: ["carrot", "pea", "corn"]
}
如果要查找数组的名称,对象中的数组上的对象处于循环中,请使用indexOf
测试对象是否存在
function findThing(thing) {
for (var k in type) {
if (type[k].indexOf(thing) > -1) return k;
}
return 'unknown';
}
console.log('An apple is a ' + findThing('apple')); // An apple is a fruit
console.log('An froom is a ' + findThing('froom')); // An froom is a unknown
另一方面,如果希望返回更多信息(如类型、大小和其他项目),可以执行以下操作:
function returnArrayOfThing(thing) {
for (var k in type) {
if (type[k].indexOf(thing) > -1) return k + ' which contains ' + type[k].length + ' items: ' + type[k];
}
return 'unknown';
}
console.log('An apple is in ' + returnArrayOfThing('apple')); // An apple is in fruit which contains 3 items: apple,banana,orange
如果您只有这两个类别,则可以执行简单的If检查:
var fruit = ["apple","banana","orange"];
var veggie = ["carrot","pea","corn"];
var typeOfApple = 'unknown';
if (fruit.indexOf('apple') !== -1) {
typeOfApple = 'fruit';
} else if (veggie.indexOf('apple') !== -1) {
typeOfApple = 'veggie';
}
alert("An apple is a " + typeOfApple);
如果您有更多的类别(或只是希望代码更健壮),则可以使用带有键的对象作为类别,并使用带有该类别项的值数组:
var types = {
fruit : ["apple","banana","orange"],
veggie : ["carrot","pea","corn"]
}
然后,您可以检查每个类别是否包含您的项目:
var typeOfApple = 'unknown';
for (var type in types) {
if (types[type].indexOf('apple') !== -1)
typeOfApple = type;
}
alert("An apple is a " + typeOfApple);
使用对象包含这两个数组,如下所示
你能更具体地说明你在问什么吗!谷歌搜索“JavaScript数组包含值函数”,然后使用该函数确定水果是否包含“苹果”而
vegige
没有。假设你不能自己编写这个函数,这是一个公平的假设,考虑到你的问题^ ^我可以使用类似fruit.contains(“apple”)
,但我正在尝试获取它,所以我不需要知道var-fruit
。
var food = {
fruit : ["apple","banana","orange"],
veggie : ["carrot","pea","corn"]
}
var arr = getFood('apple', food);
//returns ["apple","banana","orange"];
var arr2 = getFood('pea', food);
//returns ["carrot","pea","corn"];
function getFood(item, food){
for (var key in food){
if(food[key].indexOf(item) != -1){
return food[key];
}
}
}