Last evaluated expression in Javascript

Question

Is it possible in Javascript to get the result of the last evaluated expression? For example:

var a = 3;
var b = 5;
a * b;
console.log(lastEvaluatedExpression); // should print 15

So it would be something like eval() where it returns the last evaluated expression, but I cannot use eval().

Answer 1

There is no standard, reified concept of "the result of the last evaluated expression" in JavaScript. There are actually not too many languages that do have such a thing. Various JavaScript REPLs may provide some facility along these lines, but that's specific to those REPLs. Therei s no general "JavaScript" way.

Answer 2

-- package.json --

  "dependencies": {
    "stream-buffers": "^3.0.1"
  },

-- main.js --

const streamBuffers = require('stream-buffers');

const repl = require('repl');
const reader = new streamBuffers.ReadableStreamBuffer();
const writer = new streamBuffers.WritableStreamBuffer();

const r = repl.start({
    input: reader, 
    output: writer,
    writer: function (output) {
        console.log(output)
        return output;
    }
});
reader.push(`
var a = 3;
var b = 5;
a * b;`);
reader.stop();

-- output --

undefined
undefined
15

see: https://nodejs.org/api/repl.html