Question

As I can do to make child inherit the parent without altering child code constructor like this:

var parent = function(params){
    this.params = params;
}

var child = function(){}

var childObj = new child({one:1,two:2});

console.log(childObj.params) //should show params

Answer 1

You cannot. How would that work, the parameters you passed to the function (which did nothing with them) are not available from outside…

function child(p) {
    parent.call(this, p);
}

The only thing you could do to reach the expected result without modifying the constructor functiono is setting them manually:

var childObj = new child();
childObj.params = {one:1,two:2};

// or, if you want all child objects to inherit them:

child.prototype.params = {one:1,two:2};