Mark specific words with asterisks (Javascript)

Question

I have an array of objects with a set of certain words like entities. For example :

footnotes: [
  { sourceText: 'red'},
  { sourceText: 'green'},
  { sourceText: 'yellow'},
  { sourceText: 'purple'},
  { sourceText: 'gray'},
  { sourceText: 'blue'}
]

And I have some random sentences. For example: 'I drive a red car among green fields and look at the gray sky'

The goal is to mark words with asterisks according to the object of entities:

'I drive a red* car among green** fields and look at the gray*** sky'

I'm trying to do this in a loop with silce and Regexp but I can't concatenate the string correctly

How can this be done ?

Here is my code

footnotes = [{
    sourceText: "red",
    solve: false
  },
  {
    sourceText: "green",
    solve: false
  },
  {
    sourceText: 'yellow',
    solve: false
  },
  {
    sourceText: "purple",
    solve: false
  },
  {
    sourceText: "grey",
    solve: false
  },
  {
    sourceText: "blue",
    solve: false
  }
]

starGenerate = function(count) {
  let result = ''
  
  for (let i = 0; i < count; i++) {
    result += '*'
  }
  
  return result
},


let post = {
  id: 21321,
  data: {},
  lead: 'I drive a red car among green fields and look at the gray sky'
}


post.check = function() {
  let str, concat = ''
  let self = this;
  let starcounter = 0

  for (let i = 0; i < self.entities.length; i++) {
    let reg = new RegExp(`${self.entities[i].sourceText}`);

    if (match = reg.exec(self.lead) && self.entities[i].solve === false) {
      concat = self.lead.replace(reg, `${self.entities[i].sourceText + starGenerate(++starcounter)}`)
      self.entities[i].solve = true
    }
  }
}

post.entities = footnotes

You seem to have an errant comma after your function. Why is the function a property of the post object? How is it called? You might simplify and put that code in a snippet demo using the editor. — isherwood, Feb 04 '22 at 15:59

trincot · Answer 1 · 2022-02-07T10:10:42.130

You can do this with one regular expression (using |), and then use the callback argument of replace to insert the asterisks. I would prepare the replacement text for each word and place it in an object keyed by word. Your function starGenerate is not really needed, as there is the repeat method.

function putAsterisks(footnotes, sentence) {
    let alternatives = footnotes.map(({sourceText}) => sourceText).join("|");
    let replacements = Object.fromEntries(footnotes.map(({sourceText}, i) => 
        [sourceText, sourceText + "*".repeat(i + 1)]
    ));
    let regex = RegExp("\\b(" + alternatives + ")\\b", "gi");
    return sentence.replace(regex, m => replacements[m]);
}

// Example:
let footnotes = [{ sourceText: 'red'}, { sourceText: 'green'}, { sourceText: 'yellow'}, { sourceText: 'purple'}, { sourceText: 'gray'}, { sourceText: 'blue'}];
let sentence = 'I drive a red car among green fields and look at the gray sky with a red moon';

console.log(putAsterisks(footnotes, sentence));

This assumes that the source texts do not contain characters that have a special meaning in regular expressions. If this could happen, then use this answer to first escape those words.

I'd assume OP wants "I have a red* t-shirt and I drive a red* car among green** fields..." but it's not specified and the change is trivial anyway so my +1! — Adriano Repetti, Feb 07 '22 at 09:43
Thanks @AdrianoRepetti, that's a good remark. I have updated the code to use a number of stars that reflects the footnote sequence number. — trincot, Feb 07 '22 at 10:11

score 0 · Answer 2 · answered Feb 04 '22 at 16:48

You can do the same without regex by splitting your string and using map among all the words. This works fine as long as there is no further punctuation in your input string

const footnotes=[{sourceText:"red",solve:!1},{sourceText:"green",solve:!1},{sourceText:"yellow",solve:!1},{sourceText:"purple",solve:!1},{sourceText:"grey",solve:!1},{sourceText:"blue",solve:!1}];

const input = 'I drive a red car among green fields and look at the grey sky'
const footnotesIndex = footnotes.reduce( (acc,i) => (acc[i.sourceText] = i.solve,acc),{});
let star=1
const result = input.split(" ").map( word =>footnotesIndex[word] != undefined ? word + "*".repeat(star++) : word).join(" ");
console.log(result);

Mark specific words with asterisks (Javascript)

2 Answers2