LESSON 399 OF 414 · PROJECTS: COMMAND-LINE TOOLS

CLI Tool: tr v3 — Delete Chars (-d) in TypeScript

Practice

Build a version of the Unix tr -d command. Given a list of lines and a string chars, remove every character that appears in chars from each line, then return the lines joined by newline characters (\n).

Notes: chars is a non-empty ASCII string whose characters are taken literally (no ranges). Upper and lower case are different characters. A line can become empty after deleting, and then it stays as an empty line in the output.

Function signature:

trDelete(lines: string[], chars: string): string

Example:

Input: lines = ["banana", "apple"], chars = "aeiou"

Output: "bnn\nppl"

When printed:
bnn
ppl

Build a Set from chars (passing a string to the Set constructor iterates char-by-char). For each line, walk char-by-char and keep characters NOT in the set.

let set = new Set(chars);
// per char: if (!set.has(ch)) out += ch;

The full solution:

class Solution {
    trDelete(lines: string[], chars: string): string {
        let set = new Set(chars);
        let result: string[] = [];
        for (let i = 0; i < lines.length; i++) {
            let out = "";
            for (let j = 0; j < lines[i].length; j++) {
                if (!set.has(lines[i][j])) {
                    out += lines[i][j];
                }
            }
            result.push(out);
        }
        return result.join("\n");
    }
}

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CLI Tool: tr v3 — Delete Chars (-d) in TypeScript

Tr V3 in TypeScript