nodejs json.stringify a 1gb object running out of memory - json

Question

I'm trying to json.stringify a 1 gb object so that I can write it to disk. I get FATAL ERROR: JS Allocation failed - process out of memory
What can I do to stringify successfully?

Answer 1

You can stringify bit by bit manually: if y is a key of x, then JSON.stringify(y) + ":" + JSON.stringify(x[y]) gives you one segment.
Using fs.appendFileSync, for example, you can use:
var output = "out.json";
fs.writeFileSync(output, "{");
var first = true;
for(var y in x) {
if(x.hasOwnProperty(y)) {
if(first) first = false;
else fs.appendFileSync(output, ",");
fs.appendFileSync(output, JSON.stringify(y) + ":" + JSON.stringify(x[y]))
}
}
fs.appendFileSync(output, "}");
You can also use a Write Stream

Answer 2

Extended with Object, Array checker
var first, y, i$, ref$, len$, toString$ = {}.toString;
switch (toString$.call(x).slice(8, -1)) {
case 'Object':
fs.writeFileSync(output, '{');
first = true;
for (y in x) {
if (x.hasOwnProperty(y)) {
if (first) {
first = false;
} else {
fs.appendFileSync(output, ',');
}
fs.appendFileSync(output, JSON.stringify(y) + ':' + JSON.stringify(x[y]));
}
}
fs.appendFileSync(output, '}');
break;
case 'Array':
fs.writeFileSync(output, '[');
first = true;
for (i$ = 0, len$ = (ref$ = x).length; i$ < len$; ++i$) {
y = ref$[i$];
if (first) {
first = false;
} else {
fs.appendFileSync(output, ',');
}
fs.appendFileSync(output, JSON.stringify(y));
}
fs.appendFileSync(output, ']');
break;
default:
fs.writeFileSync(output, JSON.stringify(x));
}