find_heap_limit.js

// $ node -v
// v8.4.0

"use strict";
var v8 = require("v8");
console.log(v8.getHeapStatistics());

// { total_heap_size: 9437184,    
//   total_heap_size_executable: 3145728,
//   total_physical_size: 6928200,
//   total_available_size: 1490925984,
//   used_heap_size: 5717440,
//   heap_size_limit: 1501560832,
//   malloced_memory: 8192,
//   peak_malloced_memory: 5079792,
//   does_zap_garbage: 0 }