我是全新的，请原谅任何失礼。我搜索了一个解决方案，但找不到任何能回答我问题的内容，或者至少找不到任何我能理解的内容。
所以这里是：我想迭代这个数组中的每个对象，并检查firstName（＆＃34; Akira＆＃34;，在这种情况下）是否与我的＆＃中的任何firstNames匹配34;触点＆＃34;阵列。在这个阶段，我只想返回对象的索引号（如果可能的话）。如果没有，请让我知道如何以最基本的，5年的方式做到这一点。谢谢！
var contacts = [
{
"firstName": "Akira",
"lastName": "Laine",
"number": "0543236543",
"likes": ["Pizza", "Coding", "Brownie Points"]
},
{
"firstName": "Harry",
"lastName": "Potter",
"number": "0994372684",
"likes": ["Hogwarts", "Magic", "Hagrid"]
},
{
"firstName": "Sherlock",
"lastName": "Holmes",
"number": "0487345643",
"likes": ["Intriguing Cases", "Violin"]
},
{
"firstName": "Kristian",
"lastName": "Vos",
"number": "unknown",
"likes": ["Javascript", "Gaming", "Foxes"]
}
function lookUpProfile(firstName, prop){
for (var i = 0; i < contacts.length; i++) {
if (contacts[i][firstName] == firstName){
return i;
}
}
}
lookUpProfile("Akira", "likes");
答案 0 :(得分：0)
您的代码有一个错误，您的联系人变量没有关闭“]”，访问对象属性时也使用代码contacts[i]["firstname"]
var contacts = [
{
"firstName": "Akira",
"lastName": "Laine",
"number": "0543236543",
"likes": ["Pizza", "Coding", "Brownie Points"]
},
{
"firstName": "Harry",
"lastName": "Potter",
"number": "0994372684",
"likes": ["Hogwarts", "Magic", "Hagrid"]
},
{
"firstName": "Sherlock",
"lastName": "Holmes",
"number": "0487345643",
"likes": ["Intriguing Cases", "Violin"]
},
{
"firstName": "Kristian",
"lastName": "Vos",
"number": "unknown",
"likes": ["Javascript", "Gaming", "Foxes"]
}];
function lookUpProfile(firstName, prop){
var ret = -1;
for (var i = 0; i < contacts.length; i++) {
if (contacts[i]["firstName"] == firstName){
ret = i;
}
}
console.log(ret);
}
lookUpProfile("Akira", "likes");
答案 1 :(得分：0)
你可以参考this回答。 以下是访问JSON对象的最佳方法。
function lookUpProfile(firstName, prop){
for (var i = 0; i < contacts.length; i++) {
if (contacts[i]["firstName"] == firstName){
return i;
}
}
}
或
function lookUpProfile(firstName, prop){
for (var i = 0; i < contacts.length; i++) {
if (contacts[i].firstName == firstName){
return i;
}
}
}
答案 2 :(得分：0)
对象属性可以是accessed点符号，或者你必须引用你的键，因为它是一个字符串。
if (contacts[i].firstName == firstName){
return i;
}
检查fiddle
答案 3 :(得分：0)
您忘记在函数
中关闭联系人数组并调用属性错误
var contacts = [
{
"firstName": "Akira",
"lastName": "Laine",
"number": "0543236543",
"likes": ["Pizza", "Coding", "Brownie Points"]
},
{
"firstName": "Harry",
"lastName": "Potter",
"number": "0994372684",
"likes": ["Hogwarts", "Magic", "Hagrid"]
},
{
"firstName": "Sherlock",
"lastName": "Holmes",
"number": "0487345643",
"likes": ["Intriguing Cases", "Violin"]
},
{
"firstName": "Kristian",
"lastName": "Vos",
"number": "unknown",
"likes": ["Javascript", "Gaming", "Foxes"]
}
];
function lookUpProfile(firstName, prop){
for (var i = 0; i < contacts.length; i++) {
if (contacts[i].firstName === firstName){
console.log(i);
return i;
}
}
}
lookUpProfile("Sherlock", "likes");
答案 4 :(得分：0)
您的代码将变量firstName与密钥firstName混淆。
在lookUpProfile函数中，更改以下行：
if(contacts[i].firstName == firstName)
答案 5 :(得分：0)
只需更改您的功能 -
function lookUpProfile(firstName, prop){
for (var i = 0; i < contacts.length; i++) {
if (contacts[i].firstName === firstName){
return i;
}
}
}
并且不要使用＆＃39; ==＆＃39;使用＆＃39; ===＆＃39;在javaScript中
答案 6 :(得分：0)
您的代码有一些小错误，但除了那些，一切看起来都不错。第一个错误是您没有关闭contacts数组。您已在此处打开了数组：var contacts = [并开始列出联系人，但之后，您必须使用此字符]关闭此数组。
第二个问题是你真正关心的问题。当您检查firstName时，您传递的是与该函数相同的参数，也就是说，您不是在检查contacts[i].firstName === "Akira"而是contacts[i].Akira === "Akira"。并且没有任何对象具有Akira属性。
您可以尝试contacts[i].firstName或contacts[i].["firstName"]。两者都可以解决你的问题。
您可以在此处找到更多解释：http://www.w3schools.com/js/js_properties.asp
答案 7 :(得分：0)
查看您希望在函数中接受的参数，我假设您需要给定联系人的属性。
您可以使用contacts[0].firstName等点符号访问对象的属性。
您还可以使用包含contacts[0]["firstName"]等相关键的数组来访问它。
var contacts = [
{
"firstName": "Akira",
"lastName": "Laine",
"number": "0543236543",
"likes": ["Pizza", "Coding", "Brownie Points"]
},
{
"firstName": "Harry",
"lastName": "Potter",
"number": "0994372684",
"likes": ["Hogwarts", "Magic", "Hagrid"]
},
{
"firstName": "Sherlock",
"lastName": "Holmes",
"number": "0487345643",
"likes": ["Intriguing Cases", "Violin"]
},
{
"firstName": "Kristian",
"lastName": "Vos",
"number": "unknown",
"likes": ["Javascript", "Gaming", "Foxes"]
}
];
function lookUpProfile(firstName, prop){
for (var i = 0; i < contacts.length; i++) {
if (contacts[i].firstName == firstName){
console.log(i);
return contacts[i][prop];
}
}
}
console.log(lookUpProfile("Akira", "likes"));
答案 8 :(得分：0)
好的，从搜索功能开始：
// Prop parameter wasn't used so I removed it.
function lookUpProfile(firstName){
for (var i = 0; i < contacts.length; i++) {
// If you are using an array accessor for the properties you want to throw
// quotes around it. You could also access it like so contacts[i].firstName.
// What you had previously was using the value of "firstName" to try to
// access the "firstName" property. What your code actually tried was to
// access the "Akira" property which doesn't exist.
//
// Also until you get stronger in javascript it is safer to use the "==="
// strict equality as this checks for type and value equality. (ex 0 === "0" will be false)
if (contacts[i]['firstName'] === firstName){
// By returning here you are saying that no other object can have the
// same "firstName" value. If that isn't true you will want to store
// the index in a variable outside of this loop and return it later.
//
// Another option here is to just return "contacts[i]" that way you
// have a reference to the object you are searching for.
return i;
}
}
}
一般情况下，在开始时我建议使用严格相等（“===”/“！==”），因为它会表现得更直观，更快失败。如果您使用“==”/“！=”javascript将尝试为您转换类型，如果它们不匹配，可能会导致意外行为。
答案 9 :(得分：0)
如果您编写此代码，那么您将得到这样的输出 [0，未定义，未定义，未定义]。 其中0是匹配的字符索引。
var lookUpProfile = function(matchString) {
var returnVal = function(item,index) { if(item.firstName == matchString) return index; };
return returnVal;
};
var profileIndexHolder = contacts.map(lookUpProfile('Sherlock'))
console.log(profileIndexHolder);