feat: add problems

BFE.dev/4. implement basic throttle().js

@@ -0,0 +1,27 @@
+/**
+ * @param {Function} func
+ * @param {number} wait
+ */
+function throttle(func, wait) {
+    let waiting;
+    let params;
+
+    function callback() {
+        if (params) {
+            func(...params);
+            params = null;
+        }
+    }
+
+    return function (...args) {
+        params = args;
+        if (!waiting) {
+            callback();
+        }
+
+        waiting = setTimeout(() => {
+            waiting = null;
+            callback();
+        }, wait);
+    };
+}

BFE.dev/6. implement basic debounce().js

@@ -0,0 +1,14 @@
+/**
+ * @param {Function} func
+ * @param {number} wait
+ */
+function debounce(func, wait) {
+    let timer;
+    return function (...args) {
+        clearTimeout(timer);
+        timer = setTimeout(() => {
+            func(...args);
+            timer = null;
+        }, wait);
+    };
+}

BFE.dev/7. implement debounce() with leading & trailing option.js

@@ -0,0 +1,24 @@
+/**
+ * @param {Function} func
+ * @param {number} wait
+ * @param {boolean} option.leading
+ * @param {boolean} option.trailing
+ */
+function debounce(func, wait, option = { leading: false, trailing: true }) {
+    let timer;
+    let lastArgs;
+    return function betterFunction(...args) {
+        lastArgs = args;
+        clearTimeout(timer);
+        if (option.leading && !timer && lastArgs) {
+            func(...lastArgs);
+            lastArgs = null;
+        }
+        timer = setTimeout(() => {
+            if (option.trailing && lastArgs) {
+                func(...lastArgs);
+            }
+            timer = null;
+        }, wait);
+    };
+}

BFE.dev/8. can you shuffle() an array?.js

@@ -0,0 +1,9 @@
+/**
+ * @param {any[]} arr
+ */
+function shuffle(arr) {
+    for (let i = 0; i < arr.length; i++) {
+        const j = i + Math.floor(Math.random() * (arr.length - i));
+        [arr[i], arr[j]] = [arr[j], arr[i]];
+    }
+}

BFE.dev/9. decode message.js

@@ -0,0 +1,22 @@
+/**
+ * @param {string[][]} message
+ * @return {string}
+ */
+function decode(message) {
+    let ans = "";
+    let i = 0;
+    let j = 0;
+    let direction = 1;
+    while (j < message.length && i < message[0].length) {
+        ans += message[j][i];
+        i++;
+        if (j === 0) {
+            direction = 1;
+        }
+        if (j + 1 === message.length) {
+            direction = -1;
+        }
+        j += direction;
+    }
+    return ans;
+}

Leetcode/Google/929. Unique Email Addresses.js

@@ -0,0 +1,13 @@
+/**
+ * @param {string[]} emails
+ * @return {number}
+ */
+var numUniqueEmails = function (emails) {
+    const uniqueEmails = {};
+    emails.forEach(email => {
+        const [username, domainName] = email.split("@");
+        uniqueEmails[`${username.split("+")[0].replaceAll(".", "")}@${domainName}`] = 1;
+    });
+
+    return Object.keys(uniqueEmails).length;
+};