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isDeepStrictEqual() method to do object parison but am blocked by error:

util.isDeepStrictEqual() is not a function

1. According to official documentation: this method was introduced in v9.0.0 and I am using Node v12: .html#util_util_isdeepstrictequal_val1_val2

2. I confirmed this method is available on mand line:

   D:\>node
   Wele 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
   

3. 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);
    }
   

isDeepStrictEqual() method to do object parison but am blocked by error:

util.isDeepStrictEqual() is not a function

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

2. I confirmed this method is available on mand line:

   D:\>node
   Wele 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
   

3. 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);
    }
   

• javascript
• node.js
• reactjs

Share Improve this question Follow asked Sep 1, 2020 at 2:11 LLDLLD 16311 gold badge44 silver badges1414 bronze badges 1

• 1 reactjs runs on the web browser, nodejs runs on the console, they are two pletely different environment – arslan2012 Commented Sep 1, 2020 at 3:32

Add a ment  | 

2 Answers 2

Sorted by: Reset to default 5

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 mand line.

If you want to use this with "util" name:

import * as util from 'util';

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