Algo - Find Substring

Determine if string 2 is a substring of string 1

by joshpauljohnson

HTML

<form>
    <p>
        <input type="text" id="s1" placeholder="1st String"/>
        <input type="text" id="s2" placeholder="2nd String"/>
        <input type="submit" value="Is 2nd String a Substring of 1st?"/>
        <span id="out">...</span>
    </p>
</form>

JavaScript

$("form").submit(function(e) {
    e.preventDefault();
    $("#out").text('...');
    $("#out").text( isSubstr($("#s1").val(), $("#s2").val()) );
});

var isSubstr = function(s1, s2) {
    for (var i = 0; i < s1.length; i++) {
        if (s1[i] === s2[0]) {
            var found = true;
            for (var j = 0; j < s2.length && i + j < s1.length; j++) {
                if (s1[i+j] !== s2[j]) {
                    found = false;
                    break;
                }
            }
            if (found) {
                return true;
            }
        }
    }
    
    return false;
};