ticks

Author: Cyril Walle

js/tricks.md

@@ -15,19 +15,19 @@ Object.assign(scores, initialScores);
 
 ```
 const minMax = function (numbers) {
-  const results = [];
-  // variables localResult does not clash,
-  // independent blocks are used
-  {
-    const localResult = Math.min(...numbers);
-    results.push(localResult);
-  }
+    const results = [];
+    // variables localResult does not clash,
+    // independent blocks are used
+    {
+        const localResult = Math.min(...numbers);
+        results.push(localResult);
+    }
 
-  {
-    const localResult = Math.max(...numbers);
-    results.push(localResult);
-  }
-  return results;
+    {
+        const localResult = Math.max(...numbers);
+        results.push(localResult);
+    }
+    return results;
 };
 
 ```
@@ -41,3 +41,73 @@ let b = 2;
 [a, b] = [b, a];
 ```
 
+
+Remove duplicates from an array
+
+```
+let a = [5, 4, 4, 4, 3];
+a = [...(new Set(a))];
+```
+
+Object.seal and Object.freeze to ensure that an external object does not exceed an Interface
+
+```
+const requestInterface = {
+    event: undefined,
+    startDate: undefined,
+    endDate: undefined
+};
+
+const handleRequest = function (request) {
+    const minimalRequest = Object.seal(Object.assign({}, requestInterface));
+    Object.assign(minimalRequest, request);
+    processRequest(minimalRequest);
+};
+
+const processRequest = function (request) {
+    console.log(request);
+};
+
+// this will throw
+handleRequest({
+    event: undefined,
+    startDate: undefined,
+    endDate: undefined,
+    tooMuch: "data",
+    leadsTo: "leaks"
+});
+```
+
+default assignement syntax to log for required parameters
+
+```
+const required = function () {
+    throw `required parameter missing`;
+};
+
+const vector3Interface = [0, 0, 0];
+
+const slowVector3 = function (vector3 = required()) {
+    return vector3.map(u => u / 2);
+};
+
+slowVector3() --> Error: required parameter missing
+```
+
+It works really well with destructuring too
+
+
+```
+const required = function (message = "") {
+    throw `required parameter ${message} missing`;
+};
+
+const vector3Interface = [0, 0, 0];
+
+const slowVector3 = function ([x = required("x"), y = required("y"), z = required("z")] = required("v3")) {
+    return [x / 2, y / 2, z /2];
+};
+
+slowVector3([6, 8]); --> Error: required parameter z missing 
+```
+