list comprehension containing enumerate equivalent in javascript

November 9, 2021

Please what is the equivalent in javascript of this python code

guessed_index = [
        i for i, letter in enumerate(self.chosen_word)
        if letter == self.guess
    ]

Both enumerate and list comprehension are not present in the ES6 equivalent, how to I combine both ideas into one

>Solution :

Focussing on the iterable/enumerate part of your question rather than the specific task you’re performing: You can implement a JavaScript analogue of Python’s enumerate using a generator function, and consume the resulting generator (which is a superset of an iterable) via for-of (or manually if you prefer):

function* enumerate(it, start = 0) {
    let index = start;
    for (const value of it) {
        yield [value, index++];
    }
}

const word = "hello";
const guess = "l";
const guessed_indexes = [];
for (const [value, index] of enumerate(word)) {
    if (value === guess) {
        guessed_indexes.push(index);
    }
}
console.log(`guessed_indexes for '${guess}' in '${word}':`, guessed_indexes);

Or you can write a specific generator function that does the task of finding matches:

function* matchingIndexes(word, guess) {
    let index = 0;
    for (const letter of word) {
        if (letter === guess) {
            yield index;
        }
        ++index;
    }
}

const word = "hello";
const guess = "l";
const guessed_indexes = [...matchingIndexes(word, guess)];

console.log(`guessed_indexes for '${guess}' in '${word}':`, guessed_indexes);