Question

89

How to import util module in Node.js?

rated 0 times [ 92] [ 3] / answers: 1 / hits: 11037 / 4 Years ago, tue, september 1, 2020, 12:00:00

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);

 }

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mireyag

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answered 4 Years ago pranav · Accepted 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.