[javascript] How to update array value javascript?

I have an array of 3 objects of keyValue constructor in javacsript:

  function keyValue(key, value){
    this.Key = key;
    this.Value = value;
  };

  var array = [];
  array.push(new keyValue("a","1"),new keyValue("b","2"),new keyValue("c","3"));

I also have a function 'Update' which takes keyValue object as parameter and updates the value of that object in the array:

  function Update(keyValue, newKey, newValue)
  {
    //Now my question comes here, i got keyValue object here which i have to 
    //update in the array i know 1 way to do this 

    var index = array.indexOf(keyValue);
    array[index].Key = newKey;
    array[index].Value = newValue; 
  }

But I want a better way to do this if there is one.

So I had a problem I needed solved. I had an array object with values. One of those values I needed to update if the value == X.I needed X value to be updated to the Y value. Looking over examples here none of them worked for what I needed or wanted. I finally figured out a simple solution to the problem and was actually surprised it worked. Now normally I like to put the full code solution into these answers but due to its complexity I wont do that here. If anyone finds they cant make this solution work or need more code let me know and I will attempt to update this at some later date to help. For the most part if the array object has named values this solution should work.

            $scope.model.ticketsArr.forEach(function (Ticket) {
                if (Ticket.AppointmentType == 'CRASH_TECH_SUPPORT') {
                    Ticket.AppointmentType = '360_SUPPORT'
                }
            });

Full example below _____________________________________________________

   var Students = [
        { ID: 1, FName: "Ajay", LName: "Test1", Age: 20 },
        { ID: 2, FName: "Jack", LName: "Test2", Age: 21 },
        { ID: 3, FName: "John", LName: "Test3", age: 22 },
        { ID: 4, FName: "Steve", LName: "Test4", Age: 22 }
    ]

    Students.forEach(function (Student) {
        if (Student.LName == 'Test1') {
            Student.LName = 'Smith'
        }
        if (Student.LName == 'Test2') {
            Student.LName = 'Black'
        }
    });

    Students.forEach(function (Student) {
        document.write(Student.FName + " " + Student.LName + "<BR>");
    });

How about;

function keyValue(key, value){
    this.Key = key;
    this.Value = value;
};
keyValue.prototype.updateTo = function(newKey, newValue) {
    this.Key = newKey;
    this.Value = newValue;  
};

array[1].updateTo("xxx", "999");   

Why not use an object¹?

var dict = { "a": 1, "b": 2, "c": 3 };

Then you can update it like so

dict.a = 23;

or

dict["a"] = 23;

If you wan't to delete² a particular key, it's as simple as:

delete dict.a;

_{¹ See Objects vs arrays in Javascript for key/value pairs.
² See the delete operator.}

If you want to reassign an element in an array, you can do the following:

var blah = ['Jan', 'Fed', 'Apr'];

console.log(blah);

function reassign(array, index, newValue) {
    array[index] = newValue;
    return array;
}

reassign(blah, [2], 'Mar');

function Update(key, value)
{    
    for (var i = 0; i < array.length; i++) {
        if (array[i].Key == key) {
            array[i].Value = value; 
            break;
        }
    }
}