findIndex javascript problems

Question

I'm trying to findIndex of an object in an array containing multiple objects. I've been struggling with this for a while and have simplified it to what you see and still cannot get it. Please let me know what will work so that I can get the "input" object's string from matchBetween("string1");

matchBetween("string1");
matchBetween = function (result) {
        let params = [
            { param: "string1", input: "inputstring1"},
            { param: "string2", input: "inputstring2"}
            ];
        console.log(result, params, params.param ); //Output: "string1", (2)[{...}, {...
        let location = params.findIndex (x => Object.is(result, x));
        console.log(location); //outputs -1
        return params[location].input // 'Cannot read property 'input' of undefined'
    };

I've attempted multiple things, but I feel like it's an easy fix and I'm just missing it. THank you in advance!

you're Object.is is comparing each {param, input} object with a string ... so, clearly there's no match ... x=>x.param == result instead — Jaromanda X
– Jaromanda X, Commented Sep 14, 2017 at 3:45
note: params.param will always be undefined as that's not how arrays of objects works — Jaromanda X
– Jaromanda X, Commented Sep 14, 2017 at 3:46

qxg · Accepted Answer · 2017-09-14 04:48:13Z

2

Object.is(result, x) is wrong.

Run params.findIndex (x => {console.log(x); return false;}); to see what each x looks like

{param: "string1", input: "inputstring1"}
{param: "string2", input: "inputstring2"}

So you can use Object.is(result, x.param) as Jean mentioned, or result === x.param, or simply

params.find(x => x.param === result).input

Note, you need to handle when result is not found.

edited Sep 14, 2017 at 4:48

answered Sep 14, 2017 at 4:18

qxg

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Jean Michél Marca · Accepted Answer · 2017-09-14 04:00:06Z

1

Try this sample:

matchBetween = function (result) {
    let params = [
        { param: "string1", input: "inputstring1"},
        { param: "string2", input: "inputstring2"}
        ];
    console.log(result, params, params[0].param ); //Output: "string1", (2)[{...}, {...x=>x.param == result
    let location = params.findIndex (function(x) { return Object.is(result, x.param); });
    console.log(location); //outputs -1
    return params[location].input // 'Cannot read property 'input' of undefined'
}; 
console.log(matchBetween("string2"));

answered Sep 14, 2017 at 4:00

Jean Michél Marca

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