This is my data
[{name:'james',grade:'A'},
{name:'john',grade:'B'},
{name:'iris',,grade:'A'},
{name:'ivan',,grade:'C'}]
I want to keep object that has grade A and C, it's easy I can just do filter like
person.filter(obj => obj.grade === 'A' || obj.grade === 'C')
but now I have an array of object.
[{grade:'A'},{grade:'C'}]
any clue how can I do filtering now? do I need nested loop?
Use Array.prototype.some:
let person = [{name:'james', grade:'A'},
{name:'john', grade:'B'},
{name:'iris', grade:'A'},
{name:'ivan', grade:'C'}];
let predicate = [{grade:'A'},{grade:'C'}];
let result = person.filter(obj => predicate.some(p => p.grade == obj.grade))
console.log('result:', result)If your predicate is more dynamic than that, compare all object properties instead of just p.grade.
person.filter(obj => predicate.some(p => {
return Object.keys(p).every(k => obj[k] == p[k]);
}));
predicate is OP's "but now I have an array of object". person is the first array which includes names. Edited to clarify.
Using underscore lib eg -
var bbb = [
{id: 839},
{id: 854}
];
var ids = {};
_.each(bbb, function (bb) { ids[bb.id] = true; });
var data = [{grade:'A'},{grade:'C'}];
var value = {};
_.each(data , function (d) { value[data.garde] === 'A' | value[data.garde] === 'C' ; });
Objects having grades A and C should be filtered as (classic js syntax),
var a = [
{name:'james',grade:'A'},
{name:'john',grade:'B'},
{name:'iris',grade:'A'},
{name:'ivan',grade:'C'}
];
a.filter(function(e) {
return (e.grade == 'A') || (e.grade == 'C');
});
[{grade:'A'},{grade:'C'}]. His question is very misleading indeed. (I didn't downvote)If you have many grades to check (I don't know like all of them ;) ). You could first convert array into Set
const grades = new Set([{grade:'A'},{grade:'C'}].map(({grade}) => grade))
const persons = [{name:'james',grade:'A'},
{name:'john',grade:'B'},
{name:'iris',grade:'A'},
{name:'ivan',grade:'C'}]
And then filter persons array using has
const filtered = persons.filter(({grade}) => grades.has(grade))
{name:'john'} you wouldn't have to rewrite it :p (good answer though)You could use a Set for the predicates and filter accordingly
let person = [{ name: 'james', grade: 'A' }, { name: 'john', grade: 'B' }, { name: 'iris', grade: 'A' }, { name: 'ivan', grade: 'C' }],
predicate = [{ grade: 'A' }, { grade: 'C' }],
result = person.filter((s => p => s.has(p.grade))(new Set(predicate.map(p => p.grade))));
console.log(result).as-console-wrapper { max-height: 100% !important; top: 0; }