如何从数组中检索活动项目列表？

Question

I'm trying to get a list of employees who only have active hobbies and whose role is of type 'A'.

I tried using the below query but without any success.

What am I doing wrong?

 // Get all the employees with active hobbies and have a role of 'A' var employees = people.find(item => item.key === 'Employees').employees.map(emp => emp.hobbies).filter(hobby => hobby.filter(h => h.active === true && h.roles.includes('A'))); console.log(employees); 

 <script> var people = [{ key: 'Employees', employees: [{ name: 'joe', age: 20, hobbies: [{ 'active': true, name: 'skating', roles: ['C', 'A'] }] }, { name: 'amy', age: 32, hobbies: [{ 'active': true, name: 'surfing', roles: ['A'] }] }, { name: 'kate', age: 34, hobbies: [{ 'active': true, name: 'running', roles: ['C'] }, { name: 'Chess', active: false, roles: ['C', 'A'] }] } ] }]; </script> 

Update

When I added more employees with new hobbies to the array, the accepted answer fails to produce the correct output. Why does this happen?

var people = [{
        key: 'Employees',
        employees: [{
                name: 'Steve',
                age: 50,
                hobbies: [{
                        active: true,
                        name: 'skating',
                        roles: ['C', 'A']
                    },
                    {
                        active: false,
                        name: 'skating',
                        roles: ['C', 'A']
                    },
                    {
                        active: true,
                        name: 'snooker',
                        roles: ['C', 'A']
                    },
                    {
                        active: true,
                        name: 'darts',
                        roles: ['C', 'A']
                    }
                ]
            },{
                name: 'joe',
                age: 20,
                hobbies: [{
                        active: true,
                        name: 'skating',
                        roles: ['C', 'A']
                    }
                ]
            }, {
                name: 'amy',
                age: 32,
                hobbies: [{
                        'active': true,
                        name: 'surfing',
                        roles: ['A']
                    }
                ]
            }, {
                name: 'kate',
                age: 34,
                hobbies: [{
                        active: true,
                        name: 'running',
                        roles: ['C']
                    }, {
                        name: 'Chess',
                        active: false,
                        roles: ['C', 'A']
                    }
                ]
            }
        ]
    }
];

var employees = people.find(item => item.key === 'Employees').employees.filter(employee => employee.hobbies.every(h => h.active && h.roles.includes('A')));

Answer 1

If you do this:

 .map(emp => emp.hobbies).filter(hobby =>

you map every employee to its hobbies, which fill result in a 2D array:

 [[ { active: true }, { active: false } ], [/*...*/]]

Therefore hobby is not one hobby but an array of hobbies.

You said

I'm trying to get a list of employees

... which means you actually don't want to .map to the hobbies, but rather .filter the employees and check if ever hobby fullfills certain rules:

 const employees = people.find(({ key }) => key === "Employees").employees;

 const isActive = hobby => hobby.active && hobby.roles.includes("A");

 const result = employees.filter(emp => emp.hobbies.every(isActive));

Answer 2

Things go wrong where you map the employees to their hobbies: this will make your final result consist of hobbies, not employees.

You need to stick to the employee level:

 var people = [{key: 'Employees',employees: [{ name: 'joe', age: 20, hobbies: [{'active': true, name: 'skating', roles: ['C', 'A'] }] },{ name: 'amy', age: 32, hobbies: [{'active': true, name: 'surfing', roles: ['A'] }] }, { name: 'kate', age: 34, hobbies: [{'active': true, name: 'running', roles: ['C']}, {name: 'Chess', active: false, roles: ['C','A']}] }]}]; var employees = people.find(item => item.key === 'Employees').employees .filter(employee => employee.hobbies.every(h => h.active && h.roles.includes('A'))); console.log(employees); 

In an expression there is no need to compare a boolean property with true . Just use the property ( active in this case).

Use .some instead of .every if the requirement is that employees have at least one such hobby, instead of requiring that all their hobbies comply with the condition.

Answer 3

.map(emp => emp.hobbies) returns an array of the hobbies, so the value of employees will be the filtered list of hobbies, not the employees that have those hobbies. You need to filter the employees, not map them.

 // Get all the employees with active hobbies and have a role of 'A' var employees = people.find(item => item.key === 'Employees').employees.filter(emp => emp.hobbies.every(h => h.active && h.roles.includes('A'))); console.log(employees); 

 <script> var people = [{ key: 'Employees', employees: [{ name: 'joe', age: 20, hobbies: [{ 'active': true, name: 'skating', roles: ['C', 'A'] }] }, { name: 'amy', age: 32, hobbies: [{ 'active': true, name: 'surfing', roles: ['A'] }] }, { name: 'kate', age: 34, hobbies: [{ 'active': true, name: 'running', roles: ['C'] }, { name: 'Chess', active: false, roles: ['C', 'A'] }] } ] }]; </script> 

Answer 4

You can simply do one call to Array.prototype.filter which checks the conditions you mentioned:

person.hobbies.every(y => y.active) && person.hobbies.every(z => z.roles.includes('A'))

 var people = [{ key: 'Employees', employees: [{ name: 'joe', age: 20, hobbies: [{ 'active': true, name: 'skating', roles: ['C', 'A'] }] }, { name: 'amy', age: 32, hobbies: [{ 'active': true, name: 'surfing', roles: ['A'] }] }, { name: 'kate', age: 34, hobbies: [{ 'active': true, name: 'running', roles: ['C'] }, { name: 'Chess', active: false, roles: ['C', 'A'] }] } ] }]; let employees = people[0].employees.filter(x => x.hobbies.every(y => y.active) && x.hobbies.every(z => z.roles.includes('A')) ) console.log(employees); 

Answer 5

You can use map & filter :

 var people = [{ key: 'Employees', employees: [{ name: 'joe', age: 20, hobbies: [{ 'active': true, name: 'skating', roles: ['C', 'A'] }] }, { name: 'amy', age: 32, hobbies: [{ 'active': true, name: 'surfing', roles: ['A'] }] }, { name: 'kate', age: 34, hobbies: [{ 'active': true, name: 'running', roles: ['C'] }, { name: 'Chess', active: false, roles: ['C', 'A'] }] } ] }]; const result = people.filter(x => x.key == 'Employees') .map(({employees}) => employees.filter(x => x.hobbies.some(y => y.active && y.roles.includes('A')))) console.log(result) 

you could also use reduce & filter :

 var people = [{ key: 'Employees', employees: [{ name: 'joe', age: 20, hobbies: [{ 'active': true, name: 'skating', roles: ['C', 'A'] }] }, { name: 'amy', age: 32, hobbies: [{ 'active': true, name: 'surfing', roles: ['A'] }] }, { name: 'kate', age: 34, hobbies: [{ 'active': true, name: 'running', roles: ['C'] }, { name: 'Chess', active: false, roles: ['C', 'A'] }] } ] }]; const result = people.filter(x => x.key == 'Employees').reduce((r,{employees}) => { r.push(employees.filter(x => x.hobbies.some(y => y.active && y.roles.includes('A')))) return r }, []) console.log(result)