I have an array of strings ["samantha", "mike", "john", "sammy", "carla"] and an input value of s.
const input = "s"; let names = ["samantha", "mike", "john", "sammy", "carla"]; let filteredNames = names.filter(name => name.startsWith(input)); This gives me "samantha" and "sammy" as a result.
How can I extract the string that all elements of filteredNames start with? So basically: How can I find out that sam is the matching string for this array?
You can use reduce() on first element of your result array and then use every() to check if current letter is same in every element with same index.
let names = ["samantha", "sammy"]; var found = true; var r = names[0].split('').reduce(function(r, e, i) { var check = names.every(elem => elem[i] == e); check && found ? r += e : found = false; return r; }, '') console.log(r)
const input = "s" let names = ["samantha", "mike", "john", "sammy", "carla"] let fN = names.filter(name => name.startsWith(input)) let result = "" if(fN.length){ result = input for(let i=1; fN.every(x=>x[i]==fN[0][i]); i++) result += fN[0][i] } console.log(result)Not necessarily efficient, but something like:
function findCommonPrefix(array) { let prefix = ""; const smallest = findSmallestString(array); while (prefix.length < smallest) { let test = prefix + array[0][prefix.length]; if (!(array.every(item => item.indexOf(test) == 0))) return prefix; prefix = test; } return prefix; } function findSmallestString(array) { if (array.length <= 0) return -1; let smallest = Number.MAX_SAFE_INTEGER; for (let x = 0; x < array.length; x++) { const len = array[x].length; if (smallest > len) smallest = len; } return smallest; } let stuff = ["sammy", "samuel"]; console.info(findCommonPrefix(stuff)); stuff = ["sammy", "samuel", "susan"]; console.info(findCommonPrefix(stuff)); stuff = ["sammy", "samuel", "susan", "joe"]; console.info(findCommonPrefix(stuff));
filteredNames? e.g.["hat","hats","ham"]->ha?