update a JSON object with input fields' values

UPDATE

I noticed you didn't just want to get the corresponding JSON value but instead wanted to set the value. I think this will work better. new jsFiddle

obj = {
    "subscription": {
        "control-data": [
            "app",
            "sp"],
            "callback-url": "http://core.mbv:18080/man-notify",
            "post-notification": true
    },
        "charging-schedulers": [{
        "charging-scheduler-name": "fifteen-days",
    }]
}

function updateJSON() {
    var inputs = document.getElementsByTagName("input");
    for (var i = 0; i < inputs.length; i++) {
        var q = inputs[i].name.split("%$#^");
        setValue(obj, q, inputs[i].value);
    }

    // This is the updated JSON obj
    console.log(obj);
}

function setValue(obj, q, val) {
    var sel = q.shift();
    if (typeof obj[sel] === "object" && q.length > 0) {
        setValue(obj[sel], q, val);
    } else {
        obj[sel] = val;
    }
}

HTML

<input type="text" name="subscription%$#^control-data%$#^0" class="inputArea" value="app" size="3">
<input type="text" name="subscription%$#^callback-url" class="inputArea" value="http://core.mbv:18080/man-notify" size="36">
<button id="update" onclick="updateJSON()">Update</button>

You could do something like this. I am assuming your input names correspond to the structure in the JSON object. jsFiddle

var obj = {
    "subscription": {
        "control-data": [
            "app",
            "sp"],
            "callback-url": "http://core.mbv:18080/man-notify",
            "post-notification": true
    },
        "charging-schedulers": [{
        "charging-scheduler-name": "fifteen-days",
    }]
}

var inputs = document.getElementsByTagName("input");
for (var i = 0; i < inputs.length; i++) {
    var q= inputs[i].name.split("%$#^");
    var value = getValue(obj, q);

    // This is where you have the value for an input
    console.log("value:", value);
}

function getValue(obj, q) {
    var res = obj[q.shift()];
    if (typeof res === "object" && q.length > 0) {
        return getValue(res, q)
    } else {
        return res
    }
}

the function you need is a kind of data binding, and there's a lot of existing libraries to do this. they allow you to declare connections between html form fields and js variables, and synchronize their value dynamically.

rivets.js seems to be a good option for you, and you may find more similar things by searching js data binding.