Kebab file names

snippets/index-of-substrings.md

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+---
+title: Index of substrings
+tags: string,algorithm,generator
+author: chalarangelo
+cover: violin
+firstSeen: 2020-12-31T13:58:51+02:00
+lastUpdated: 2020-12-31T13:58:51+02:00
+---
+
+Finds all the indexes of a substring in a given string.
+
+- Use `Array.prototype.indexOf()` to look for `searchValue` in `str`.
+- Use `yield` to return the index if the value is found and update the index, `i`.
+- Use a `while` loop that will terminate the generator as soon as the value returned from `Array.prototype.indexOf()` is `-1`.
+
+```js
+const indexOfSubstrings = function* (str, searchValue) {
+  let i = 0;
+  while (true) {
+    const r = str.indexOf(searchValue, i);
+    if (r !== -1) {
+      yield r;
+      i = r + 1;
+    } else return;
+  }
+};
+```
+
+```js
+[...indexOfSubstrings('tiktok tok tok tik tok tik', 'tik')]; // [0, 15, 23]
+[...indexOfSubstrings('tutut tut tut', 'tut')]; // [0, 2, 6, 10]
+[...indexOfSubstrings('hello', 'hi')]; // []
+```