如何确保javascript检查所有属性
嗨,我正在尝试检查联系人是否存在,是否有特定属性,然后返回如何确保javascript检查所有属性,javascript,loops,properties,Javascript,Loops,Properties,嗨,我正在尝试检查联系人是否存在,是否有特定属性,然后返回 var contacts = [ { "firstName": "Akira", "lastName": "Laine", "number": "0543236543", "likes": ["Pizza", "Coding", "Brownie Points"] }, { "firstName": "Harry", "lastName": "Potter", "number":
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 lookUp(firstName, prop) {
var i;
for (i = 0; i < contacts.length; i++) {
if (contacts[i].firstName === firstName && contacts[i].hasOwnProperty(prop)) {
return contacts[i][prop];
} else if (contacts[i].firstName !== firstName) {
return "No such contact";
} else if (contacts[i].firstName === firstName && contacts[i].hasOwnProperty(prop) === false) {
return "No such property";
}
}
}
lookUp("Harry", "likes");
var联系人=[
{
“名字”:“Akira”,
“姓氏”:“莱恩”,
“编号”:“0543236543”,
“喜欢”:[“披萨”、“编码”、“布朗尼点数”]
},
{
“名字”:“哈利”,
“姓氏”:“波特”,
“编号”:“0994372684”,
“喜欢”:[“霍格沃茨”、“魔法”、“海格”]
},
{
“名字”:“夏洛克”,
“姓氏”:“福尔摩斯”,
“编号”:“0487345643”,
“喜欢”:[“有趣的案例”,“小提琴”]
},
{
“名字”:“克里斯蒂安”,
“姓氏”:“Vos”,
“编号”:“未知”,
“喜欢”:[“Javascript”、“游戏”、“狐狸”]
},
];
函数查找(名字,道具){
var i;
对于(i=0;i
问题是,它只返回循环中的第一个结果,因此在本例中,它只检查联系人[0]的firstName===firstName,然后返回false,即使联系人[1]firstName===firstName尝试以下操作:
// Returns:
// contact prop if: contact with prop found
// true if: contact found, but not prop
// false if: not contact found
function lookUp(firstName, prop) {
var i, nameFound = false;
// Starts a loop that looks every contact until the list ends or until firstName with prop is found
for (i = 0; i < contacts.length; i++) {
if (contacts[i].firstName === firstName ) {
// If found, the function return the property "prop" of the contact named "firstName"
// Note that if there is 2 persons with the same name and both has prop, it returns the first one on the list
if(contacts[i].hasOwnProperty(prop)){
return contacts[i][prop];
}
else{
nameFound = true;
}
}
}
// If the script reach this place, it's because the person wasn't found or was found but hasn't the prop
return nameFound;
}
//返回:
//联系道具如果:找到道具联系
//如果:找到联系人,但未找到道具,则为true
//如果未找到联系人,则为false
函数查找(名字,道具){
变量i,nameFound=false;
//开始一个循环,查找每个联系人,直到列表结束或找到带prop的firstName
对于(i=0;i
试试这个:
// Returns:
// contact prop if: contact with prop found
// true if: contact found, but not prop
// false if: not contact found
function lookUp(firstName, prop) {
var i, nameFound = false;
// Starts a loop that looks every contact until the list ends or until firstName with prop is found
for (i = 0; i < contacts.length; i++) {
if (contacts[i].firstName === firstName ) {
// If found, the function return the property "prop" of the contact named "firstName"
// Note that if there is 2 persons with the same name and both has prop, it returns the first one on the list
if(contacts[i].hasOwnProperty(prop)){
return contacts[i][prop];
}
else{
nameFound = true;
}
}
}
// If the script reach this place, it's because the person wasn't found or was found but hasn't the prop
return nameFound;
}
//返回:
//联系道具如果:找到道具联系
//如果:找到联系人,但未找到道具,则为true
//如果未找到联系人,则为false
函数查找(名字,道具){
变量i,nameFound=false;
//开始一个循环,查找每个联系人,直到列表结束或找到带prop的firstName
对于(i=0;i
函数查找(名字,道具){
var i;
对于(i=0;i
函数查找(名字,道具){
var i;
对于(i=0;i
要检查对象是否具有属性,您只需检查if(obj[prop])
。
我喜欢这类东西:
function lookUp (firstName, prop) {
return contacts.reduce(
function (found, contact) {
if (contact[prop] && contact.firstName === firstName)
found.push(contact);
return found;
}, []
);
}
要检查对象是否有属性,您只需选中if(obj[prop])。 我喜欢这类东西:
function lookUp (firstName, prop) {
return contacts.reduce(
function (found, contact) {
if (contact[prop] && contact.firstName === firstName)
found.push(contact);
return found;
}, []
);
}
您已经将那些
return
语句编码到循环的中间。因此,如果数组中的第一个对象不匹配,则函数立即返回。你根本不需要那些else
子句。循环结束后,只需返回“No-this-property”。
可能结果不清楚(至少对我来说)。如果找到多个结果,该怎么办?谢谢@Pointy的帮助您将return
语句编码到循环的中间。因此,如果数组中的第一个对象不匹配,则函数立即返回。你根本不需要那些else
子句。循环结束后,只需返回“No-this-property”。
可能结果不清楚(至少对我来说)。如果发现多个结果,会发生什么?谢谢@Pointy that worked抱歉,我不得不编辑它以使返回为false;在循环之外。对不起,我必须编辑它以使返回为假;循环外部。它只是在联系人
数组上迭代,对于每个联系人,如果满足条件,将其推送到保存找到的每个联系人的数组中。解释起来有点复杂,但你可以在a贴的链接中阅读更多内容。您也可以在本书中阅读更多关于迭代器函数的内容。它只需迭代联系人
数组,对于每个联系人,如果满足条件,将其推送到保存找到的每个联系人的数组中。解释起来有点复杂,但你可以读m