Replace all occurrence of specific words in a sentence based on an array of words in JavaScript

We are required to write a JavaScript function that takes a string and an array of strings.

Our function should return a new string, where all the occurrences of the word in the string that are present in the array are replaced by a whitespace.

Our function should use the String.prototype.replace() method to solve this problem.

Understanding the Problem

When filtering words from a sentence, we need to:

• Match whole words only (not parts of words)
• Handle case-insensitive matching
• Use regular expressions for efficient replacement

Example Implementation

Here's a complete solution using String.prototype.replace() with regular expressions:

var excludeWords = ["A", "ABOUT", "ABOVE", "ACROSS", "ALL", "ALONG", "AM",
"AN", "AND", "ANY", "ASK", "AT", "AWAY", "CAN", "DID", "DIDN'T", "DO",
"DON'T", "FOR", "FROM", "HAD", "HAS", "HER", "HIS", "IN", "INTO", "IS",
"IT", "NONE", "NOT", "OF", "ON", "One", "OUT", "SO", "SOME", "THAT",
"THE", "THEIR", "THERE", "THEY", "THESE", "THIS", "TO", "TWIT", "WAS",
"WERE", "WEREN'T", "WHICH", "WILL", "WITH", "WHAT", "WHEN", "WHY"];

var sentence = "The first solution does not work for any UTF-8 alphaben. I have managed to create function which do not use RegExp and use good UTF-8 support in JavaScript engine. The idea is simple if symbol is equal in uppercase and lowercase it is special character. The only exception is made for whitespace.";

const removeExcludedWords = (str, words) => {
    // Create regex pattern with word boundaries for exact word matching
    const regex = new RegExp(`\b(${words.join('|')})\b`, 'gi');
    // Replace matched words with empty string
    return str.replace(regex, "");
};

console.log(removeExcludedWords(sentence, excludeWords));

first solution does work UTF-8 alphaben. I have managed create function use RegExp use good UTF-8 support JavaScript engine. idea simple if symbol equal uppercase lowercase special character. only exception made whitespace.

How It Works

The solution uses several key components:

• \b - Word boundaries ensure we match complete words only
• words.join('|') - Creates an alternation pattern (word1|word2|word3)
• 'gi' flags - Global and case-insensitive matching
• replace(regex, "") - Replaces all matches with empty string

Alternative Approach with Space Replacement

If you prefer to replace excluded words with spaces instead of removing them entirely:

const removeExcludedWordsWithSpaces = (str, words) => {
    const regex = new RegExp(`\b(${words.join('|')})\b`, 'gi');
    return str.replace(regex, " ").replace(/\s+/g, " ").trim();
};

var testSentence = "The quick brown fox jumps over the lazy dog";
var commonWords = ["the", "over"];

console.log("Original:", testSentence);
console.log("Filtered:", removeExcludedWordsWithSpaces(testSentence, commonWords));

Original: The quick brown fox jumps over the lazy dog
Filtered: quick brown fox jumps lazy dog

Key Points

• Word boundaries (\b) prevent partial word matches
• Case-insensitive flag ('i') handles different capitalizations
• Global flag ('g') replaces all occurrences, not just the first
• The pipe operator (|) creates an OR pattern in regex

Conclusion

Using String.prototype.replace() with regular expressions provides an efficient way to remove multiple words from a sentence. The key is using word boundaries and proper regex flags for accurate matching.