How can I use Array find method in JavaScript: expected undefined to equal '2015'?

Question

I am trying to write a function that uses find() to return the year of superbowl win ("W"). This is the array object

const record = [
{ year: "2018", result: "N/A"},
{ year: "2017", result: "N/A"},
{ year: "2016", result: "N/A"},
{ year: "2015", result: "W"},
{ year: "2014", result: "N/A"},
{ year: "2013", result: "L"},
{ year: "2012", result: "N/A"},
{ year: "2011", result: "N/A"},
{ year: "2010", result: "N/A"},
{ year: "2009", result: "N/A"},
{ year: "2008", result: "N/A"},
{ year: "2007", result: "N/A"},
{ year: "2006", result: "N/A"},
{ year: "2005", result: "N/A"},
{ year: "2004", result: "N/A"},
{ year: "2003", result: "N/A"},
{ year: "2002", result: "N/A"},
{ year: "2001", result: "N/A"},
{ year: "2000", result: "N/A"},
{ year: "1999", result: "N/A"},
{ year: "1998", result: "W"},
{ year: "1997", result: "W"},
{ year: "1996", result: "N/A"},
{ year: "1995", result: "N/A"},
{ year: "1994", result: "N/A"},
{ year: "1993", result: "N/A"},
{ year: "1992", result: "N/A"},
{ year: "1991", result: "N/A"},
{ year: "1990", result: "N/A"},
{ year: "1989", result: "L"},
{ year: "1988", result: "N/A"},
{ year: "1987", result: "L"},
{ year: "1986", result: "L"},
{ year: "1985", result: "N/A"},
{ year: "1984", result: "N/A"},
{ year: "1983", result: "N/A"},
{ year: "1982", result: "N/A"},
{ year: "1981", result: "N/A"},
{ year: "1980", result: "N/A"},
{ year: "1979", result: "N/A"},
{ year: "1978", result: "N/A"},
{ year: "1977", result: "N/A"},
{ year: "1976", result: "L"},
{ year: "1975", result: "N/A"},
{ year: "1974", result: "N/A"},
{ year: "1973", result: "N/A"},
{ year: "1972", result: "N/A"},
{ year: "1971", result: "N/A"},
{ year: "1970", result: "N/A"},
{ year: "1969", result: "N/A"},
{ year: "1968", result: "N/A"},
{ year: "1967", result: "N/A"},
{ year: "1966", result: "N/A"},
{ year: "1965", result: "N/A"},
{ year: "1964", result: "N/A"},
{ year: "1963", result: "N/A"},
{ year: "1962", result: "N/A"},
{ year: "1961", result: "N/A"},
{ year: "1960", result: "N/A"}
]


function superbowlWin (element){
    if(element.result === "W"){
    const winYear = element.year
    return winYear;
    }
}


console.log(record.find(superbowlWin).year);`

My tests fail with the error below:

superbowlWin(record) 1) returns a year the Denver Broncos won the superbowl ✓ returns undefined if the record has no win objects

1 passing (377ms) 1 failing

1. superbowlWin(record). returns a year the Denver Broncos won the superbowl. AssertionError: expected undefined to equal '2015' at Context. (test/indexTest.js:66:33) at processImmediate (internal/timers.js:461:21)

I was expecting the return winYear to equal 2015.

Answer 1

Your problem is when there is no value for your find request. The return value is undefined then you are trying to get the year of an undefined object.

Try:

    function superbowlWin(records){
        const winRecord = records.find(element => element.result === "W");
        return winRecord ? winRecord.year : undefined;
    }

console.log(superbowlWin(record));

The line return winRecord ? winRecord.year : undefined; checks if the winRecord has value if yes return the year if not return undefined.