hijack.js

hijack.js

var hijack = function(that, name, wrap) {
    var f0 = that[name];
    that[name] = function() {
        var f = function() {
            f0.apply(that, arguments);
        };
        var args = Array.prototype.slice.call(arguments);
        args.unshift(f);
        return wrap.apply(null, args);
    };
};

// Example:
//
//   hijack(gl, 'drawArrays', function(f, mode, first, count) {
//      console.log('gl.drawArrays(', mode, first, count, ')');
//      return f(mode, first, count);
//  });
//