检查阵列输入 - Javascript

我是全新的，所以请原谅任何失礼。我寻找解决方案，但找不到解决我的问题的任何事情，或者至少我能理解的任何事情。检查阵列输入 - Javascript

所以在这里：我想遍历数组中的每个对象，并检查firstName（在本例中为“Akira”）是否与我的“contacts”数组中的任何firstName匹配。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岁的方式来做到这一点。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");

来源

2016-12-15 hello hi

var answer = lookUpProfile（“Akira”）; –

你的代码中有你就没有结束“]”为您的联系人的错误变量，也当访问对象属性使用代码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");

来源

2016-12-15 06:53:47

你可以参考this答案。以下是访问JSON对象的最佳方式。

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; 
    } 
    } 
}

来源

2016-12-15 06:53:53

对象属性可以通过accessed点符号，或者你有你的报价键它是一个字符串。

if (contacts[i].firstName == firstName){ 
    return i; 
}

检查fiddle

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2016-12-15 06:53:59 Afsar

你忘了收起来触点阵列，并呼吁物业错在函数内部

var contacts = [ 
 
\t { 
 
\t \t "firstName": "Akira", 
 
\t \t "lastName": "Laine", 
 
\t \t "number": "0543236543", 
 
\t \t "likes": ["Pizza", "Coding", "Brownie Points"] 
 
\t }, 
 
\t { 
 
\t \t "firstName": "Harry", 
 
\t \t "lastName": "Potter", 
 
\t \t "number": "0994372684", 
 
\t \t "likes": ["Hogwarts", "Magic", "Hagrid"] 
 
\t }, 
 
\t { 
 
\t \t "firstName": "Sherlock", 
 
\t \t "lastName": "Holmes", 
 
\t \t "number": "0487345643", 
 
\t \t "likes": ["Intriguing Cases", "Violin"] 
 
\t }, 
 
\t { 
 
\t \t "firstName": "Kristian", 
 
\t \t "lastName": "Vos", 
 
\t \t "number": "unknown", 
 
\t \t "likes": ["Javascript", "Gaming", "Foxes"] 
 
\t } 
 
]; 
 

 
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");

来源

2016-12-15 06:54:35

您的代码混淆变量的firstName的关键名字。

在你lookUpProfile功能，改变这一行：

if(contacts[i].firstName == firstName)

Explanation

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2016-12-15 06:54:47 Anuja

只要改变你的函数一样 -

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 '==' 使用“== ='in javaScript

来源

2016-12-15 06:55:22 Viplock

你的代码有一些小错误，但除了那些，一切看起来都很好。第一个错误是你没有关闭联系人数组。您已在此处打开阵列：var contacts = [并开始列出联系人，但在此之后，您必须使用此字符]关闭此阵列。

第二个问题是你真正关心的问题。当您检查firstName时，您传递的是与您给该函数相同的参数，这就是说，您不在检查是否contacts[i].firstName === "Akira"，而是contacts[i].Akira === "Akira"。而且没有任何物体具有晃性质。您可以尝试contacts[i].firstName或contacts[i].["firstName"]。两者都可以解决你的问题。

您可以在这里找到更多的解释：http://www.w3schools.com/js/js_properties.asp

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2016-12-15 06:57:31

看着你想在函数接受的参数，我假设你想给定的接触特性。

您可以使用点符号（如contacts[0].firstName）访问对象的属性。

你也可以使用数组和关联键来访问它，如contacts[0]["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){ 
 
    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"));

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2016-12-15 06:58:01 josephting

好了，所以开始与你的搜索功能：

// 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; 
    } 
    } 
}

一般开始的时候出来我会建议使用严格的平等（ “===”/“== “），因为它会表现得更直观，而且会更快失败。如果你使用“==”/“！=”，javascript会尝试为你转换类型，如果它们不匹配，可能导致意想不到的行为。

来源

2016-12-15 06:58:19 Adrian

如果你写这个代码，那么你会得到像这样的输出 [0，undefined，undefined，undefined]。其中0是您的匹配字符索引。

 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);

来源

2016-12-15 07:46:29 Rjoydip

检查阵列输入 - Javascript

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