Repository: eslint/eslint
File: lib/source-code/token-store/utils.js (JavaScript)

Code before:
 * If it was not found, this returns `tokens.length`.
 * @param {(Token|Comment)[]} tokens It searches the token in this list.
 * @param {number} location The location to search.
 * @returns {number} The found index or `tokens.length`.
 */
exports.search = function search(tokens, location) {
    const index = tokens.findIndex(el => location <= getStartLocation(el));

    return index === -1 ? tokens.length : index;
};

/**
 * Gets the index of the `startLoc` in `tokens`.
 * `startLoc` can be the value of `node.range[1]`, so this checks about `startLoc - 1` as well.
 * @param {(Token|Comment)[]} tokens The tokens to find an index.
 * @param {Object} indexMap The map from locations to indices.
 * @param {number} startLoc The location to get an index.
 * @returns {number} The index.
 */
exports.getFirstIndex = function getFirstIndex(tokens, indexMap, startLoc) {
    if (startLoc in indexMap) {
        return indexMap[startLoc];
    }
    if ((startLoc - 1) in indexMap) {
        const index = indexMap[startLoc - 1];
        const token = tokens[index];

        /*
         * For the map of "comment's location -> token's index", it points the next token of a comment.
         * In that case, +1 is unnecessary.
         */
        if (!token || token.range[0] >= startLoc) {
            return index;
        }
        return index + 1;
    }
    return 0;
};

/**
 * Gets the index of the `endLoc` in `tokens`.
 * The information of end locations are recorded at `endLoc - 1` in `indexMap`, so this checks about `endLoc - 1` as well.
 * @param {(Token|Comment)[]} tokens The tokens to find an index.
 * @param {Object} indexMap The map from locations to indices.
 * @param {number} endLoc The location to get an index.
 * @returns {number} The index.
 */
exports.getLastIndex = function getLastIndex(tokens, indexMap, endLoc) {
    if (endLoc in indexMap) {
        return indexMap[endLoc] - 1;
    }

Review comment (suggestion):
If `index` is out of bounds, `token` will be `undefined`. No need to check explicitly in JavaScript.

Code after:
 * If it was not found, this returns `tokens.length`.
 * @param {(Token|Comment)[]} tokens It searches the token in this list.
 * @param {number} location The location to search.
 * @returns {number} The found index or `tokens.length`.
 */
exports.search = function search(tokens, location) {
    const index = tokens.findIndex(el => location <= getStartLocation(el));

    return index === -1 ? tokens.length : index;
};

/**
 * Gets the index of the `startLoc` in `tokens`.
 * `startLoc` can be the value of `node.range[1]`, so this checks about `startLoc - 1` as well.
 * @param {(Token|Comment)[]} tokens The tokens to find an index.
 * @param {Object} indexMap The map from locations to indices.
 * @param {number} startLoc The location to get an index.
 * @returns {number} The index.
 */
exports.getFirstIndex = function getFirstIndex(tokens, indexMap, startLoc) {
    if (startLoc in indexMap) {
        return indexMap[startLoc];
    }
    if ((startLoc - 1) in indexMap) {
        const index = indexMap[startLoc - 1];
        const token = tokens[index];

        // If the mapped index is out of bounds, the returned cursor index will point after the end of the tokens array.
        if (!token) {
            return tokens.length;
        }

        /*
         * For the map of "comment's location -> token's index", it points the next token of a comment.
         * In that case, +1 is unnecessary.
         */
        if (token.range[0] >= startLoc) {
            return index;
        }
        return index + 1;
    }
    return 0;
};

/**
 * Gets the index of the `endLoc` in `tokens`.
 * The information of end locations are recorded at `endLoc - 1` in `indexMap`, so this checks about `endLoc - 1` as well.
 * @param {(Token|Comment)[]} tokens The tokens to find an index.
 * @param {Object} indexMap The map from locations to indices.
 * @param {number} endLoc The location to get an index.
 * @returns {number} The index.