How to get the depth of a recursive array in JavaScript?

[SubhanUllah]

/* 
 * Return the depth of recursive array a. 
 * Any array has a depth of at least one. 
 * Non-arrays always have a depth of zero. 
 */ 
function arrayDepth(a) { 
    var depth = 0; 
    if (Array.isArray(a)) { 
        for (var i in a) { 
            depth = Math.max(depth, arrayDepth(a[i])); 
        } 
        depth++; 
    } 
    return depth; 
}