如何检查字符串或数组中单词的多次出现

Question

I need to get the count of a specified set duplicate words in a string.

I can return the occurrences of one word but I am stuck at multiple words.

const sData = 'am=1&am=2&pm=1&pm=2&pm=3&ac=1&dc=1';
const aData = sData.split('&');

const nData = aData.filter(el => el.includes('am')).length;

This returns 2 which is expected but I need to do the same for pm , ac and dc and as I understand includes does not accept multiple values.

Answer 1

You can encompass repeated work using functions !

const countOccurrencesOf = (word, search) => {
  return word.filter(el => el.includes(search)).length;
};

Now, you can re-use this function for all of your other string finding needs:

countOccurrencesOf(aData, 'pm');
countOccurrencesOf(aData, 'ac');
countOccurrencesOf(aData, 'dc');

Answer 2

What you're looking for, is a recursive function. Within the example you have provided, I'm assuming your parsing URL Query variables. So, let's pretend that the following are your delimiters: & or =.

This function shows a general idea of what it seems like you're trying to acheive.

 function containsDuplicates(string,delimiter,foundDuplicates){
    var str = string.split(delimiter);

    if(foundDuplicates.includes(str)){
        return true;
    }else if(string.indexOf(str) < string.length){
        foundDuplicates.push(str);
        return containsDuplicates(string,delimiter,foundDuplicates);
    }
    else{
        return false;
    }
}

Answer 3

Try using map instead:

const sData = 'am=1&am=2&pm=1&pm=2&pm=3&ac=1&dc=1';
const aData = sData.split('&');

// define the stings you want to count
const nData = {am: 0, pm: 0, ac: 0}

// iterate over the split input data
const val = aData.map((obj) => {
    // iterate over the nData
    Object.keys(nData).forEach((count) => {
        // if the input contains the count, add to the count
        if (obj.includes(count)) nData[count]++;
    })
})
console.log(nData); // returns: { am: 2, pm: 3, ac: 1 }

Reduce would probably work as well!

Answer 4

• Create an array of keywords you want to find.
• Create a regex by separating the words with a | .
• Use match get all the matches for the keywords specified.
• Create a counter object. Loop through the array of matches and count each occurrence

 const str = 'am=1&am=2&pm=1&pm=2&pm=3&ac=1&dc=1', toFind = ['am', 'pm', 'ac'], regex = new RegExp(toFind.join("|"), "g"), matches = str.match(regex); console.log(matches) const counter = {}; matches.forEach(m => counter[m] = counter[m] + 1 || 1) console.log(counter) 

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