var diff = jdp.diff = function()

in pytheas-core/src/main/resources/js/jsondiffpatch.js [190:273]
72 lines of code
36 McCabe index (conditional complexity)

    var diff = jdp.diff = function(o, n){
        var ntype, otype, nnull, onull, d;
        
        if (o === n) {
            return;
        }
        if ((o !== o) && (n !== n)) {
            return; // o and n are both NaN
        }
        ntype = typeof n;
        otype = typeof o;
        nnull = n === null;
        onull = o === null;

        // handle Date objects
        if (otype == 'object' && isDate(o)){
            otype = 'date';
        }
        if (ntype == 'object' && isDate(n)){
            ntype = 'date';
            if (otype == 'date'){
                // check if equal dates
                if (o.getTime() === n.getTime()){
                    return;
                }
            }
        }
        
        if (nnull || onull || ntype == 'undefined' || ntype != otype ||
        ntype == 'number' ||
        otype == 'number' ||
        ntype == 'boolean' ||
        otype == 'boolean' ||
        ntype == 'string' ||
        otype == 'string' ||
        ntype == 'date' ||
        otype == 'date' ||
        ((ntype === 'object') && (isArray(n) != isArray(o)))) {
            // value changed
            d = [];
            if (typeof o != 'undefined') {
                if (typeof n != 'undefined') {
                    var longText = (ntype == 'string' && otype == 'string' && Math.min(o.length, n.length) > jdp.config.textDiffMinLength);
                    if (longText && !jdp.config.textDiff) {
                        diff_match_patch_autoconfig();
                    }
                    if (longText && jdp.config.textDiff) {
                        // get changes form old value to new value as a text diff
                        d.push(jdp.config.textDiff(o, n), 0, 2);
                    }
                    else {
                        // old value changed to new value
                        d.push(o);
                        d.push(n);
                    }
                }
                else {
                    // old value has been removed
                    d.push(o);
                    d.push(0, 0);
                }
            }
            else {
                // new value is added
                d.push(n);
            }
            return d;
        }
        else {
            if (isArray(n)) {
                // diff 2 arrays    
                if (n._key || o._key) {
                    return arrayDiffByKey(o, n, n._key || o._key);
                }
                else {
                    return arrayDiff(o, n);
                }
            }
            else {
                // diff 2 objects
                return objectDiff(o, n);
            }
        }
    };