Form data to Json file as object - php

Question

My json object should look like below, which is generating on submiting the form:
{
"range":{
"l1_price":
{"from":"0", "to":"260k", "price": "Rs .02"},
"l2_price":
{"from":"260k", "to":"500k", "price": "Rs .04"},
"l3_price":
{"from":"500k", "to":"1MM", "price": "Rs .007"},
"l4_price":
{"from":"1MM", "to":"2MM", "price": "Rs .003"}
}
}
Now the form is like:
<form class="json_out">
<p>
l1_price:
<input type="text" name="from_l1" placeholder="from range">
<input type="text" name="to_l1" placeholder="to range">
<input type="text" name="price_l1" placeholder="price">
</p>
<p>
l2_price:
<input type="text" name="from_l2" placeholder="from range">
<input type="text" name="to_l2" placeholder="to range">
<input type="text" name="price_l2" placeholder="price">
</p>
<p>
l3_price:
<input type="text" name="from_l3" placeholder="from range">
<input type="text" name="to_l3" placeholder="to range">
<input type="text" name="price_l3" placeholder="price">
</p>
<p>
l4_price:
<input type="text" name="from_l4" placeholder="from range">
<input type="text" name="to_l4" placeholder="to range">
<input type="text" name="price_l4" placeholder="price">
</p>
<p>
<input type="submit" value="Submit">
<input type="reset" value="Reset">
</p>
</form>
Finally i want to send the data to data.json file on submitting the form.
JavaScript code:
<script>
$('form.json_out').submit(function(e) {
var values = {};
var range = {};
var rates = [];
var thresholds = [];
var result = {};
e.preventDefault();
$.each($('form.json_out').serializeArray(), function(i, field) {
if(field.name){
temp = {};
name_split = field.name.split('_');
price_lev = name_split[1] + '_' + 'price';
val_str = name_split[0];
val = field.value;
temp[val_str] = val
if (val_str == 'price'){rates.push(val)};
if (val_str == 'to'){thresholds.push(val)};
if (range[price_lev]){
res = range[price_lev]
res[val_str] = val
range[price_lev] = res
}
else{
range[price_lev] = temp;
}
}
});
result['range'] = range
result['rates'] = rates
result['thresholds'] = thresholds
});
</script>