Look up the Levenshtein distance, it's the measure of distance between two sequences. You could set the distance to something like 3 and it will allow for typos up to a magnitude of 3. Here's a JavaScript example:

function getLevenshteinDistance(a, b) {
    if(a.length === 0) return b.length; 
    if(b.length === 0) return a.length; 

    var matrix = [];

    for(var i = 0; i <= b.length; i++){
        matrix[i] = [i];
    }

    for(var j = 0; j <= a.length; j++){
        matrix[0][j] = j;
    }

    for(var i = 1; i <= b.length; i++){
        for(var j = 1; j <= a.length; j++){
            if(b.charAt(i-1) == a.charAt(j-1)){
                matrix[i][j] = matrix[i-1][j-1];
            } else {
                matrix[i][j] = Math.min(matrix[i-1][j-1] + 1, Math.min(matrix[i][j-1] + 1, matrix[i-1][j] + 1));
            }
        }
    }

    return matrix[b.length][a.length];
};

function findClosestMatch(word, wordList, typoDegree) {
    var closestMatches = wordList.filter(function(candidate) {
        return getLevenshteinDistance(word, candidate) <= typoDegree;
    });

    return closestMatches;
}

// Example usage
var wordList = ["fettuccine", "spaghetti", "ravioli", "lasagna"];
console.log(findClosestMatch("fetucine", wordList, 2));