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assert.notDeepEqual() function in Node.js
The assert module provides a bunch of different functionalities that are used for function assertion. The Assert.notDeepEqual() checks inequality between the actual and expected paramters. Also the parameters should not be deep equal. An error will be thrown if the condition is not fulfilled.
Syntax
assert.notDeepEqual(actual, expected[, message])
Parameters
The above parameters are described as below −
actual – This parameter will hold the actual value which needs to be compared.
expected – This will hold the expected parameter value that needs to be checked with.
message – This is an optional parameter. This is a user defined message printed when the function is executed and any error occurs.
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 – assertNotDeepEqual.js and copy the below code snippet. After creating the file use the below command to run this code.
node assertNotDeepEqual.js
assertNotDeepEqual.js
// Importing the module
const assert = require('assert').strict;
try {
// Both the values should not be identical
assert.notDeepEqual({ a: '21' }, { a: '21' });
} catch(error) {
console.log("Error: ", error)
}Output
C:\home
ode>> node assertNotDeepEqual.js Error: { AssertionError [ERR_ASSERTION]: Identical input passed to notDeepStrictEqual: { a: '21' } at Object.<anonymous> (/home/mayankaggarwal/mysql-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' }
Example
Let's take a look at one more example.
// Importing the module
const assert = require('assert').strict;
try {
// Both the values should not be identical
assert.notDeepEqual({ a: 21 }, { a: '21' });
console.log("Values are not identical")
} catch(error) {
console.log("Error: ", error)
}Output
C:\home
ode>> node assertNotDeepEqual.js Values are not identical
We can see in the above example that one value is of type string whereas the other value is of type integer which is why they are not equal.
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