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assert.notDeepStrictEqual() function in Node.js
The assert module provides a bunch of different functionalities that are used for function assertion. The assert.notDeepStrictEqual tests that two objects should not be deep strict equal. An assertion error is thrown if both the objects are strictly equal.
Syntax
assert.notDeepStrictEqual(actual, expected, [message])
Parameters
The above parameters are described as below −
actual – This parameter contains the actual value that needs to be compared.
expected – This parameter will hold the expected values to be evaluated agains the actual parameters.
message – This is an optional parameter. This is a user defined message printed when the function is executed.
Installing the Assert Module
npm install assert
The assert module is an inbuilt Node.js module, so you can skip this step as well. You can check the assert version using the following command to get the latest assert module.
npm version assert
Importing the module in your function
const assert = require("assert").strict;Example
Create a file with the name – notDeepStrictEqual.js and copy the below code snippet. After creating the file use the below command to run this code.
node notDeepStrictEqual.js
notDeepStrictEqual.js
// Importing the module
const assert = require('assert').strict;
try {
// Checking if actual and expected parameters are equal
assert.notDeepStrictEqual({ a: '21' }, { a: '24' });
console.log("Objects are not equal")
} catch(error) {
console.log("Error: ", error)
}Output
C:\home
ode>> node notDeepStrictEqual.js Objects are not equal
Example
Let's take a look at one more example.
// Importing the module
const assert = require('assert').strict;
try {
// Checking if actual and expected parameters are equal
assert.notDeepStrictEqual({ a: '21' }, { a: '21' });
console.log("Objects are not equal")
} catch(error) {
console.log("Error: ", error)
}Output
C:\home
ode>> node notDeepStrictEqual.js Error: { AssertionError [ERR_ASSERTION]: Identical input passed to notDeepStrictEqual: { a: '21' } at Object. (/home/node/test/assert.js:6:9) at Module._compile (internal/modules/cjs/loader.js:778:30) at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10) at Module.load (internal/modules/cjs/loader.js:653:32) at tryModuleLoad (internal/modules/cjs/loader.js:593:12) at Function.Module._load (internal/modules/cjs/loader.js:585:3) at Function.Module.runMain (internal/modules/cjs/loader.js:831:12) at startup (internal/bootstrap/node.js:283:19) at bootstrapNodeJSCore (internal/bootstrap/node.js:623:3) generatedMessage: true, name: 'AssertionError [ERR_ASSERTION]', code: 'ERR_ASSERTION', actual: { a: '21' }, expected: { a: '21' }, operator: 'notDeepStrictEqual' }
We can see that in the above example both the values are 21 and of string type.
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