Add Hello World Script

Javascript/elloWorld.js

@@ -0,0 +1,79 @@
+// Usage: $ node HelloRube/Javascript/elloWorld.js Hello World
+
+let input = "";
+process.argv.forEach((val, index, array) => {
+  if ([0, 1].indexOf(index) === -1) {
+    if (index !== 2) {
+      val = ` ${val}`;
+    }
+    input += val;
+  }
+});
+
+const ALPHABET = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ ".split(
+  ""
+);
+
+const transformTextCharacterToAlphabetIndex = array => {
+  return new Promise((resolve, reject) => {
+    const indexArray = array.map(character => {
+      const index = ALPHABET.indexOf(character);
+      if (index !== -1) {
+        return index;
+      }
+    });
+    resolve(indexArray);
+  });
+};
+
+const transformAlphabetIndexToCharacterArray = array => {
+  return new Promise((resolve, reject) => {
+    const characterArray = array.map(index => {
+      return ALPHABET[index];
+    });
+    resolve(characterArray);
+  });
+};
+
+const convertToArray = text => {
+  return new Promise((resolve, reject) => {
+    resolve(text.split(""));
+  });
+};
+
+const convertToString = text => {
+  return new Promise((resolve, reject) => {
+    resolve(text.join(""));
+  });
+};
+
+class HelloWorld {
+  constructor(text) {
+    this.text = text;
+  }
+
+  async transform(initialText) {
+    let promises = [
+      convertToArray,
+      transformTextCharacterToAlphabetIndex,
+      transformAlphabetIndexToCharacterArray,
+      convertToString
+    ];
+    let lastResult = initialText;
+    for (let i = 0; i < promises.length; i++) {
+      lastResult = await promises[i](lastResult);
+    }
+    return lastResult;
+  }
+
+  say() {
+    if (this.text === "" || this.text === undefined) {
+      console.log("You forgot to enter some text...");
+      return;
+    }
+    this.transform(this.text)
+      .then(text => console.log(text))
+      .catch(error => console.log(error));
+  }
+}
+new HelloWorld(input).say();