How to compare two arrays of strings, find all matches, when there might be a sentence?

This is a fun one – I am building a profanity checker!

For the purposes of this exercise, let’s have an array of forbidden words, like so:

const forbiddenWords = ['apples', 'oranges', 'blue carrots', 'mushy green peas'];

Then I will have an input field for a user to input the something. It could be an infinite combo of words, but I would like to find ALL instances of the forbidden words and return them as an array. I’ve thought of this function, which gets me really close:

const forbiddenWords = ['apples', 'oranges', 'blue carrots', 'mushy green peas'];
const userInput = 'Broccoli is my favorite food. I hate oranges and blue carrots';

    const checkIfValidInput = () => {
        // Will return an array that looks like: ['Broccoli', 'is', 'my', 'favorite', ...]
        const splitWords = userInput.split(" ");
        const array = [];
        for (let i in forbiddenWords) {
            if (splitWords.indexOf(forbiddenWords[i]) !== -1) {
                array.push(forbiddenWords[i]);
            }
        }
        return array.sort((x, y) => x - y);
    };

JavaScript
​x
 
const forbiddenWords = ['apples', 'oranges', 'blue carrots', 'mushy green peas'];
const userInput = 'Broccoli is my favorite food. I hate oranges and blue carrots';
​
    const checkIfValidInput = () => {
        // Will return an array that looks like: ['Broccoli', 'is', 'my', 'favorite', ...]
        const splitWords = userInput.split(" ");
        const array = [];
        for (let i in forbiddenWords) {
            if (splitWords.indexOf(forbiddenWords[i]) !== -1) {
                array.push(forbiddenWords[i]);
            }
        }
        return array.sort((x, y) => x - y);
    };
​

Running the above will make the result of array be ['oranges', 'blue', 'carrots']. How could I build out the function to check for 'blue carrots' or 'mushy green peas' all in one? I’d like the above function to return: ['oranges', 'blue carrots']. Thoughts?

Answer

You can use regex for this situation. This will also give you ability to match with case insensitivity

const checkIfValidInput = () => {
  const forbiddenWords = ['apples', 'oranges', 'blue carrots', 'mushy green peas'];
  const userInput = 'Broccoli is my favorite food. I hate oranges and blue carrots';
  
  const result = forbiddenWords.reduce((acc, words) => {
    const match = userInput.match(new RegExp(words, ['gi']))
    return match ? acc.concat(match) : acc
  }, [])
  result.sort()
  console.log(result)
}

checkIfValidInput()

JavaScript
 
const checkIfValidInput = () => {
  const forbiddenWords = ['apples', 'oranges', 'blue carrots', 'mushy green peas'];
  const userInput = 'Broccoli is my favorite food. I hate oranges and blue carrots';
  
  const result = forbiddenWords.reduce((acc, words) => {
    const match = userInput.match(new RegExp(words, ['gi']))
    return match ? acc.concat(match) : acc
  }, [])
  result.sort()
  console.log(result)
}
​
checkIfValidInput()

Also, array.sort((x, y) => x - y); is not required as the values you have are string. You can rely on array.sort() or if you really want to do manual sort, try string.localeCompare(string2)

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Answer