Add examples

Author: tshemsedinov

JavaScript/1-iterator.js

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+'use strict';
+
+const iterator = {
+  counter: 0,
+  next() {
+    return {
+      value: this.counter++, // current value
+      done: this.counter > 3 // boolean
+    };
+  }
+};
+
+const step1 = iterator.next();
+const step2 = iterator.next();
+const step3 = iterator.next();
+const step4 = iterator.next();
+console.log({ step1, step2, step3, step4 });

JavaScript/2-iterable.js

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+'use strict';
+
+const iterable = {
+  [Symbol.iterator]() {
+    let i = 0;
+    const iterator = {
+      next() {
+        return {
+          value: i++,
+          done: i > 3
+        };
+      }
+    };
+    return iterator;
+  }
+};
+
+// Usage
+
+const iterator = iterable[Symbol.iterator]();
+const step1 = iterator.next();
+const step2 = iterator.next();
+const step3 = iterator.next();
+const step4 = iterator.next();
+console.log({ step1, step2, step3, step4 });
+
+for (const step of iterable) {
+  console.log({ step });
+}
+
+console.log({ steps: [...iterable] });

JavaScript/3-class.js

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+'use strict';
+
+class Counter {
+  constructor(begin, end, step = 1) {
+    this.begin = begin;
+    this.end = end;
+    this.step = step;
+  }
+  [Symbol.iterator]() {
+    const end = this.end;
+    let i = this.begin;
+    const iterator = {
+      next() {
+        return {
+          value: i++,
+          done: i > end
+        };
+      }
+    };
+    return iterator;
+  }
+}
+
+// Usage
+
+const iterable = new Counter(0, 3);
+
+const iterator = iterable[Symbol.iterator]();
+const step1 = iterator.next();
+const step2 = iterator.next();
+const step3 = iterator.next();
+const step4 = iterator.next();
+console.log({ step1, step2, step3, step4 });
+
+for (const step of iterable) {
+  console.log({ step });
+}
+
+console.log({ steps: [...iterable] });

JavaScript/4-array.js

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+'use strict';
+
+const iterable = [0, 1, 2];
+
+const iterator = iterable[Symbol.iterator]();
+const step1 = iterator.next();
+const step2 = iterator.next();
+const step3 = iterator.next();
+const step4 = iterator.next();
+console.log({ step1, step2, step3, step4 });
+
+for (const step of iterable) {
+  console.log({ step });
+}
+
+console.log({ steps: [...iterable] });

JavaScript/5-generator.js

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+'use strict';
+
+const gen = function* () {
+  let i = 0;
+  while (true) {
+    if (i >= 3) return;
+    yield i++;
+  }
+};
+
+{
+  const iterable = gen();
+  const iterator = iterable[Symbol.iterator]();
+  const step1 = iterator.next();
+  const step2 = iterator.next();
+  const step3 = iterator.next();
+  const step4 = iterator.next();
+  console.log({ step1, step2, step3, step4 });
+}
+
+{
+  const iterable = gen();
+  for (const step of iterable) {
+    console.log({ step });
+  }
+}
+
+{
+  const iterable = gen();
+  console.log({ steps: [...iterable] });
+}

JavaScript/6-yield.js

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+'use strict';
+
+const gen = function* () {
+  yield* [0, 1, 2];
+};
+
+{
+  const iterable = gen();
+  const iterator = iterable[Symbol.iterator]();
+  const step1 = iterator.next();
+  const step2 = iterator.next();
+  const step3 = iterator.next();
+  const step4 = iterator.next();
+  console.log({ step1, step2, step3, step4 });
+}
+
+{
+  const iterable = gen();
+  for (const step of iterable) {
+    console.log({ step });
+  }
+}
+
+{
+  const iterable = gen();
+  console.log({ steps: [...iterable] });
+}