Data records ///"id,first,last,emailn" + "555,John,Doe,jd@gmail.comn" + "666,Jason,scott,js@gmail.comn" + ............

var search = init(
"id,first,last,emailn" +
"555,John,Doe,jd@gmail.comn" +
"666,Jason,scott,js@gmail.comn",
"email");

search("js@gmail.com"); /// -> {"id":"666","first":"Jason","last":"scott", "email":"js@gmail.com"}

function init(text, key) {
    var arr = text.split('n'); /// convert text to array
    var keyIndex = arr[0].split(',').indexOf(key); /// returns 3

    return function (value) {
        for (var i = 1; i < arr.length; i++) {
            var dataLine = arr[i].split(','); /// "666,Jason,scott,js@gmail.comn" to array
            if (dataLine[keyIndex] === value) { /// found match between value and id
                return convertToObject(arr[0].split(','), dataLine);
            }
        }
        return "not found";
    }
}



function convertToObject(indexLine, dataLine) {
    /// creates an object from 2 lines: {email: "js@gmail.com",first: "Jason", id: "666", last: "scott"}
    var obj = {};
    var result = "";
    for (var j = 0; j < dataLine.length; j++) {
        obj[indexLine[j]] = dataLine[j];
    }
    return JSON.stringify(obj); /// String format;
}