In MongoDB, you can perform a case-insensitive search by using the `$regex` operator along with the `i` option for case-insensitivity.
Here is an example where we are searching for “java” in the “language” field in a case-insensitive manner:
```
db.collection.find({ language: { $regex: /java/i } })
```
In this case, “/java/i” is a regular expression where “java” is what you are searching for and “i” is a flag to specify case-insensitivity.
Or, you can also specify it in a more extended way:
```
db.collection.find({ language: { $regex: /^java$/i } })
```
In this case, “^” means the beginning of a string, and “$” means the end of a string.
If you want to do it in JavaScript:
```
db.collection.find({ language: { $regex: new RegExp(‘^’ + ‘java’ + ‘$’, ‘i’) } })
```
The ‘i’ option can be added to the RegExp constructor in the second parameter to make the search case insensitive.
