Create basic-grep.js

Author: programandoconro

Languages/JavaScript/nodejs/basic-grep.js

@@ -0,0 +1,60 @@
+// Program to filter lines of a file that include a word and paint the match. Like basic grep command.
+// TODO add cli input
+
+import { readFile } from "node:fs/promises";
+import chalk from "chalk";
+
+const main = async () => {
+  let text;
+  try {
+    text = await readFile("history.txt", "utf-8");
+  } catch (error) {
+    if (error.code === "ENOENT") {
+      console.log("Not such file in path");
+      return
+    } else {
+      throw error;
+    }
+  }
+  const history = text.split("\n");
+
+  searchWord(history, "node");
+};
+
+const searchWord = (arr, word) => {
+  arr.forEach((line) => {
+    if (line.includes(word)) {
+      paintWord(line, word);
+    }
+  });
+};
+
+const paintWord = (text, searchWord) => {
+  const matches = [...text.matchAll(new RegExp(searchWord, "gi"))];
+  const startIndexes = matches.map((match) => match.index);
+  const indexes = getWordIndexes(startIndexes, searchWord.length);
+
+  let word = "";
+  text.split("").forEach((letter, index) => {
+    if (indexes.includes(index)) {
+      word += chalk.blue(letter);
+    } else {
+      word += letter;
+    }
+  });
+  console.log(word);
+};
+
+const getWordIndexes = (indices, len) => {
+  const result = [];
+
+  indices.forEach((index) => {
+    for (let i = 0; i < len; i++) {
+      result.push(index + i);
+    }
+  });
+
+  return result;
+};
+
+main();