How to map a javascript array to another javascript array

I guess you are misunderstanding map(). Here is a very simple example:

a = [1, 2, 3]
b = a.map(function (i) { return i + 1 })
// => [2, 3, 4]

Here is the MDN documentation for map: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map. So you should rethink the usage of map in your case. By the way - your example is not working, because values is not a function.

Here is a possible solution:

res = [];
a = [['a1','b1'],['a1','b2']];

for (var i = 0; i < a.length; ++i) {
  for(var j = 0; j < a[i].length; ++j) {
    res.push({"Key": i + 1 , "Value" : a[i][j]});
  }
}

I'm sure there are other ways, but here's something with plain Javascript that does what you want:

http://jsfiddle.net/KXBRw/

function Test(key, values) {
    this.Key = key;
    this.Values = values;//values.map(values);
}

function getCombinedTests(testObjectArray) {
    var all = [];
    for (var i = 0; i < testObjectArray.length; i++) {
        var cur = testObjectArray[i];
        for (var j = 0; j < cur.Values.length; j++) {
            all.push({"Key": ""+cur.Key, "Value": cur.Values[j]});
        }
    }
    return all;
}

var testObjectArray1 = [];
testObjectArray1.push(new Test(1, ['a1','b1']), new Test(2, ['a1','b2']));

var combined = getCombinedTests(testObjectArray1);

console.log(combined);

You could use .reduce(), .concat() and .map() for this.

var result = testObjectArray.reduce(function(res, obj) {
    return res.concat(obj.Values.map(function(val) {
        return {"Key":obj.Key, "Value":val};
    }));
}, []);

Not sure what values.map(values); was supposed to do though.

DEMO: http://jsfiddle.net/BWNGr/

[
    {
        "Key": 1,
        "Value": "a1"
    },
    {
        "Key": 1,
        "Value": "b1"
    },
    {
        "Key": 2,
        "Value": "a1"
    },
    {
        "Key": 2,
        "Value": "b2"
    }
]

If you're super strict about not creating unnecessary Arrays, you can tweak it a little and use .push() instead of .concat().

var result = testObjectArray.reduce(function(res, obj) {
    res.push.apply(res, obj.Values.map(function(val) {
        return {"Key":obj.Key, "Value":val};
    }));
    return res;
}, []);

DEMO: http://jsfiddle.net/BWNGr/1/

You can achieve this by using the following for each loop where each key value pair will be pushed to an array.

var mapped = [];
$.each(testObjectArray, function(key, value) { 
  for(x in value.Values) {
    mapped.push({
      Key: value.Key,
      Value: x
    });
  }
});

So, I am learning coding and was trying to learn more about the map() implementation. I came across this and these answers made me think of a way to utilize map() to do what the OP originally wanted. Is it the best way to do it? I don't know, but it technically works similar to what I think OP's goal was and helped me to understand how map() works a bit better.

let anArray = [{thingy: 'thing', num: 1, bool: true, color: 'blue', numTwo: 3}];
let newArray = anArray.map((item) => {
    return item;
});

console.log(newArray) will display the same thing anArray displays.

Please let me know if I'm wrong!

This is not for this question, but can be related to similar questions: JavaScript Map with index:

nums.map((num, index) => num + index)
// [1, 1, 1] => [1, 2, 3]