Suppose I have a javascript array of objects that looks like this:
[
{
"title": "The Great Peace",
"copyversion": 1
},
{
"title": "History of World War II",
"copyversion": 1
},
{
"title": "Crime and Punishment",
"copyversion": 2
},
{
"title": "War and Peace",
"copyversion": 2
}
]
Now, suppose that I have a search string, like "War" or "and". I want to get an array of objects where "title" contains the search string (case insensitive), but I want to ALSO include any sibling values with matching "copyversion" values.
For example:
Search string of "Great" should yield the below result, because even though "History of World War II" does not have "Great" in it, it matches the copyversion of something that does.
[
{
"title": "The Great Peace",
"copyversion": 1
},
{
"title": "History of World War II",
"copyversion": 1
}
]
Another example:
Search string of "Peace" would yield the original array. "History of World War II" is included because it has the same copyversion value as "The Great Peace", and "Crime and Punishment" is included because it has the same copyversion as "War and Peace"
[
{
"title": "The Great Peace",
"copyversion": 1
},
{
"title": "History of World War II",
"copyversion": 1
},
{
"title": "Crime and Punishment",
"copyversion": 2
},
{
"title": "War and Peace",
"copyversion": 2
}
]
If no matches are found, then an empty array would result.
I'm looking for a reasonable fast way to do this. I'm fine with pure javascript or a library like lodash.
That is my simple and readable solution. Hope it will useful for you
const books = [
{
"title": "The Great Peace",
"copyversion": 1
},
{
"title": "History of World War II",
"copyversion": 1
},
{
"title": "Crime and Punishment",
"copyversion": 2
},
{
"title": "War and Peace",
"copyversion": 2
}
];
const findBooks = (titlePart) => {
const regexp = new RegExp(`${titlePart}`, 'i');
const resultSet = new Set();
const copyVersionsSet = new Set();
// Find all books which has titlePart in title
for (const book of books) {
if (regexp.test(book.title)) {
resultSet.add(book);
copyVersionsSet.add(book.copyversion);
}
}
// Find all books which has same copyversion as found books
for (const book of books) {
if (copyVersionsSet.has(book.copyversion)) {
resultSet.add(book);
}
}
return [...resultSet];
}
console.log(findBooks('hIsToRy'));Solution contains two parts:
The first part may be optimized - we don't have to remove duplicates.
const a = [
{
"title": "The Great Peace",
"copyversion": 1
},
{
"title": "History of World War II",
"copyversion": 1
},
{
"title": "Crime and Punishment",
"copyversion": 2
},
{
"title": "War and Peace",
"copyversion": 2
}
];
const copyFinder = (word, arr) => {
const rx = new RegExp(`${word}`, 'i');
const versions = arr.reduce((collector, value) => {
if(rx.test(value.title) && collector.indexOf(value.copyversion) === -1) {
collector.push(value.copyversion);
}
return collector;
}, []);
if(versions.length === 0) {
return [];
}
return arr.filter(x => versions.indexOf(x.copyversion) > -1);
}
console.log(copyFinder('History', a));Here's one approach:
const findMatches = (books = []) => (
search = "",
lc = search .toLowerCase (),
matches = new Set (books .filter (({title}) => title .toLowerCase () .includes (lc))),
versions = new Set ([...matches] .map (({copyversion}) => copyversion))
) => books .filter ((book) => matches .has (book) || versions .has (book .copyversion))
const books = [{"title": "The Great Peace", "copyversion": 1}, {"title": "History of World War II", "copyversion": 1}, {"title": "Crime and Punishment", "copyversion": 2}, {"title": "War and Peace", "copyversion": 2}]
console .log ('crime: ', findMatches (books) ('crime'))
console .log ('great: ', findMatches (books) ('great'))
console .log ('war: ', findMatches (books) ('war')).as-console-wrapper {max-height: 100% !important; top: 0}We take the lower-case version of the search string, use that to filter the list to those with matching titles, storing them as a Set, then mapping them to their versions, again storing as a Set, and finally filter the original list of books to select those in that matches set or whose versions are in the version one.
Although I choose to work in this style, using defaulted parameters in place of local variables when feasible, there is a potential down-side, if findMatches (books) is used in certain ways, such as being passed to map. If that's a concern, this version does the same thing in a slightly more complex manner, without those potential problems, as the only parameters it knows about are books and search:
const findMatches = (books = []) => (search = "") => ((
lc = search .toLowerCase (),
matches = new Set (books .filter (({title}) => title .toLowerCase () .includes (lc))),
versions = new Set ([...matches] .map (({copyversion}) => copyversion))
) => books .filter ((book) => matches .has (book) || versions .has (book .copyversion)))()