JSON Output format

[avinash2015]

I have following JSON format which comes dynamically:
{
"JSON": [
{
"key": "a",
"val": "aaa",
"sub": [
{
"key": "b",
"val": "bbb"
}
]
}
]
}
And I want to convert it in following output:

{
"JSON": [
{
"a": "aaa",
"sub": [
{
"b": "bbb"
}
]
}
]
}

Instead of key word I want actual Key-Value and instead of value word I want actual value.
So where to modify form2js.
My HTML is:

: