How to import util module in Node.js?

Question

isDeepStrictEqual() method to do object comparison but am blocked by error:
util.isDeepStrictEqual() is not a function

According to official documentation: this method was introduced in v9.0.0 and I am using Node v12: https://nodejs.org/api/util.html#util_util_isdeepstrictequal_val1_val2

I confirmed this method is available on command line:
D:>node
Welcome to Node.js v12.18.2.
Type ".help" for more information.
> require("util").isDeepStrictEqual({'name': 'john'}, {'sex': 'male'})
false
> require("util").isDeepStrictEqual({'sex': 'john'}, {'sex': 'male'})
false
> require("util").isDeepStrictEqual({'sex': 'male'}, {'sex': 'male'})
true

Here is my code:
class App extends Component {

constructor(props) {
     super(props);
     var util = require('util');
     var obj1 = {name: 'john'};
     var obj2 = {sex: 'male'};
     var result = util.isDeepStrictEqual(obj1, obj2);
 }

Glitch_Znab · Answer

I dont know if you have done this so first do this
util-npm
npm install util

And adding on to the @3limin4t0r answer I don't think util should be declared in the constructor.
have it as a global constant outside the class
for example
const util = require('util');

class Foo {
  constructor() {
    this.a = 42;
  }

bar(callback) {
    callback(null, this.a);
  }
}

const foo = new Foo();

const naiveBar = util.promisify(foo.bar);
// TypeError: Cannot read property 'a' of undefined
// naiveBar().then(a => console.log(a));

naiveBar.call(foo).then((a) => console.log(a)); // '42'

const bindBar = naiveBar.bind(foo);
bindBar().then((a) => console.log(a)); // '42'

which was the example for promisify right below Util doc(isDeepStrictEqual)
So either use it as a global constant or use it directly as you have used in the command line.

How to import util module in Node.js?

One Answer

Add your own answers!

Ask a Question