java heap space error when converting csv to json but no error with d3.csv() - scala

Question

Platform being used: Apache Zeppelin
Language: scala, javascript
I use d3js to read a csv file of size ~40MB and it works perfectly fine with the below code:
<script type="text/javascript">
d3.csv("test.csv", function(data) {
// data is JSON array. Do something with data;
console.log(data);
});
</script>
Now, the idea is to avoid d3js, instead, construct the JSONarray in scala and access this variable in javascript code through z.angularBind(). Both of the below code works for smaller files, but gives java heap space error for the CSV file of size 40MB. What I am unable to understand is when d3.csv() can perfectly do the job without any heap space error, why cannot these 2 below code?
Edited Code 1: Using scala's
import java.io.BufferedReader;
import java.io.FileReader;
import org.json._
import scala.io.Source
var br = new BufferedReader(new FileReader("/root/test.csv"))
var contentLine = br.readLine();
var keys = contentLine.split(",")
contentLine = br.readLine();
var ja = new JSONArray();
while (contentLine != null) {
var splits = contentLine.split(",")
var i = 0
var jo = new JSONObject()
for(i <- 0 to splits.length-1){
jo.put(keys(i), splits(i));
}
ja.put(jo);
contentLine = br.readLine();
}
//z.angularBind("ja",ja.toString()) //ja can be accessed now in javascript (EDITED-10/11/15)
Edited Code 2:
I thought the heap space issue might go away if I use Apache spark to construct the JSON array like in below code, but this one too gives heap space error:
def myf(keys: Array[String], value: String):String = {
var splits = value.split(",")
var jo = new JSONObject()
for(i <- 0 to splits.length-1){
jo.put(keys(i), splits(i));
}
return(jo.toString())
}
val csv = sc.textFile("/root/test.csv")
val firstrow = csv.first
val header = firstrow.split(",")
val data = csv.filter(x => x != firstrow)
var g = data.map(value => myf(header,value)).collect()
// EDITED BELOW 2 LINES-10/11/15
//var ja= g.mkString("[", ",", "]")
//z.angularBind("ja",ja) //ja can be accessed now in javascript

Answer 1

You are creating JSON-objects. They are not native to java/scala and will therefore take up more space in that environment. What does z.angularBind() really do?
Also what is the heap size of your javascript environment (see https://www.quora.com/What-is-the-maximum-size-of-a-JavaScript-object-in-browser-memory for chrome) and your java environment (see How is the default java heap size determined?).
Update: Removed the original part of the answer where I misunderstood the question