Merge pull request #51 from nickovchinnikov/lesson-4-5

Typescript part 2 lesson
nickovchinnikov · Jul 15, 2020 · bb2b756 · bb2b756
2 parents 4ee7b17 + 36011dd
commit bb2b756
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Showing 7 changed files with 62 additions and 25 deletions.
diff --git a/README.md b/README.md
@@ -58,6 +58,18 @@ React and JSX
 
 [Presentation](https://docs.google.com/presentation/d/1R7sU2VQHHgCExYgX1yEKrcbwhebYSQq_OII5LY4pZuI/edit?usp=sharing)
 
+## Lesson 4.5:
+Typescript: Part 2
+
+* Generics
+* Classes
+* Indexed types/mapped types/infer
+* React+Typescript: common pitfalls
+
+[Pull request](https://github.com/nickovchinnikov/react-js-tutorial/pull/51)
+[Presentation](https://docs.google.com/presentation/d/1ucC_6gpybB52DN9tQjDF6SMsmQcdopwchdbp6jVAzOM/edit?usp=sharing)
+
+
 ## Lesson 5:
 * JSX + CSS
 * Project architecture

diff --git a/lessons/lesson13/homework/pureFunctions.ts b/lessons/lesson13/homework/pureFunctions.ts
@@ -6,7 +6,10 @@
 // };
 
 // // Задание 2
-// export type QsObj = Record<string, string | number | boolean | object>;
+export type QsObj = Record<
+  string,
+  string | number | boolean | string[] | number[] | boolean[]
+>;
 
 // export const createQs = (qsObj: QsObj): string => {
 //   //

diff --git a/lessons/lesson4.5/generics.ts b/lessons/lesson4.5/generics.ts
@@ -0,0 +1,6 @@
+// Playground for ArrayLike generic illustration
+const divNodeList = document.querySelectorAll("div");
+
+const divArray = Array.from(divNodeList);
+
+divArray.pop();
diff --git a/scripts/calc/engine.ts b/scripts/calc/engine.ts
@@ -1,5 +1,5 @@
 import { ParsedLineType, parser } from "./parser";
-import { isNumber } from "./helpers";
+import { isOperator, isTrigonometricOperator } from "./helpers";
 import {
   mathOperators,
   mathPriorities,
@@ -14,7 +14,7 @@ export const zeroPrioritiesCalc = (stack: ParsedLineType): ParsedLineType =>
   stack.reduce<ParsedLineType>((result, item) => {
     const prevItem = result[result.length - 1];
 
-    if (!isNumber(String(item)) && mathOperatorsPriorities[item] === ZERO) {
+    if (isOperator(item) && mathOperatorsPriorities[item] === ZERO) {
       if (!mathOperators[item]) {
         throw new TypeError("Unexpected stack!");
       }
@@ -31,7 +31,7 @@ export const firstPrioritiesCalc = (stack: ParsedLineType): ParsedLineType =>
     const prevItem = result[result.length - 2];
     const item = result[result.length - 1];
 
-    if (!isNumber(String(item)) && mathOperatorsPriorities[item] === FIRST) {
+    if (isOperator(item) && mathOperatorsPriorities[item] === FIRST) {
       if (!mathOperators[item]) {
         throw new TypeError("Unexpected stack!");
       }
@@ -55,10 +55,10 @@ export const secondPrioritiesCalc = (stack: ParsedLineType): ParsedLineType =>
     const prevItem = result[result.length - 1];
 
     if (
-      !isNumber(String(prevItem)) &&
+      isTrigonometricOperator(prevItem) &&
       mathOperatorsPriorities[prevItem] === SECOND
     ) {
-      if (!isNumber(String(item))) {
+      if (isOperator(item)) {
         throw new TypeError("Unexpected stack!");
       }
       result = [
@@ -76,10 +76,7 @@ export const thirdPrioritiesCalc = (stack: ParsedLineType): ParsedLineType =>
     const prevItem = result[result.length - 2];
     const item = result[result.length - 1];
 
-    if (!isNumber(String(item)) && mathOperatorsPriorities[item] === THIRD) {
-      if (!mathOperators[item]) {
-        throw new TypeError("Unexpected stack!");
-      }
+    if (isOperator(item) && mathOperatorsPriorities[item] === THIRD) {
       result = [
         ...result.slice(0, -2),
         mathOperators[item](Number(prevItem), Number(nextItem)),
@@ -95,13 +92,14 @@ export const fourthPrioritiesCalc = (stack: ParsedLineType): number =>
     const item = stack[key - 1];
 
     if (
-      mathOperatorsPriorities[item] === SECOND ||
-      mathOperatorsPriorities[item] === THIRD
+      isOperator(item) &&
+      (mathOperatorsPriorities[item] === SECOND ||
+        mathOperatorsPriorities[item] === THIRD)
     ) {
       throw new TypeError("Unexpected stack!");
     }
 
-    if (!isNumber(String(item)) && mathOperatorsPriorities[item] === FOURTH) {
+    if (isOperator(item) && mathOperatorsPriorities[item] === FOURTH) {
       result = mathOperators[item](Number(result), Number(nextItem));
     }
     return result;

diff --git a/scripts/calc/helpers.ts b/scripts/calc/helpers.ts
@@ -1 +1,9 @@
-export const isNumber = (item: string): boolean => !isNaN(Number(item));
+import { trigonomenticOperators, mathOperators } from "./mathOperators";
+import type { MathOperator, TrigonomenticOperator } from "./mathOperators";
+
+export const isOperator = (item: string | number): item is MathOperator =>
+  item in mathOperators;
+
+export const isTrigonometricOperator = (
+  item: string | number
+): item is TrigonomenticOperator => item in trigonomenticOperators;
diff --git a/scripts/calc/mathOperators.ts b/scripts/calc/mathOperators.ts
@@ -27,7 +27,11 @@ export const tg: FunctionOperationType = (value) =>
 export const ctg: FunctionOperationType = (value) =>
   parseFloat((cos(value) / sin(value)).toFixed(2));
 
-export const scalarOperators: { [key: string]: ScalarOperationType } = {
+export type ScalarOperator = "*" | "/" | "+" | "-" | "^" | "!";
+
+export const scalarOperators: {
+  [key in ScalarOperator]: ScalarOperationType;
+} = {
   "*": mul,
   "/": div,
   "+": add,
@@ -36,17 +40,21 @@ export const scalarOperators: { [key: string]: ScalarOperationType } = {
   "!": factorial,
 };
 
+export type TrigonomenticOperator = "sin" | "cos" | "tg" | "ctg";
+
 export const trigonomenticOperators: {
-  [key: string]: FunctionOperationType;
+  [key in TrigonomenticOperator]: FunctionOperationType;
 } = {
   sin: sin,
   cos: cos,
   tg: tg,
   ctg: ctg,
 };
 
+export type MathOperator = ScalarOperator | TrigonomenticOperator;
+
 export const mathOperators: {
-  [key: string]: ScalarOperationType | FunctionOperationType;
+  [key in MathOperator]: ScalarOperationType | FunctionOperationType;
 } = {
   ...scalarOperators,
   ...trigonomenticOperators,
@@ -56,7 +64,9 @@ export const mathPriorities: number[] = [0, 1, 2, 3, 4];
 
 const [ZERO, FIRST, SECOND, THIRD, FOURTH] = mathPriorities;
 
-export const mathOperatorsPriorities: { [key: string]: number } = {
+export const mathOperatorsPriorities: {
+  [key in MathOperator]: number;
+} = {
   "!": ZERO,
   "^": FIRST,
   sin: SECOND,

diff --git a/scripts/calc/parser.ts b/scripts/calc/parser.ts
@@ -1,4 +1,4 @@
-import { isNumber } from "./helpers";
+import { isOperator } from "./helpers";
 import {
   mathOperators,
   mathOperatorsPriorities,
@@ -15,17 +15,17 @@ export const parser = (line: string): ParsedLineType | null => {
   return stack.reduce<ParsedLineType>((result, item, key) => {
     const prevItem = stack[key - 1];
 
-    const isValidNumberPush = !isNumber(prevItem) && isNumber(item);
+    const isValidNumberPush =
+      (isOperator(prevItem) || prevItem == undefined) && !isOperator(item);
     const isValidOperatorPush =
-      (isNumber(prevItem) || mathOperatorsPriorities[prevItem] === ZERO) &&
-      !isNumber(item) &&
+      (!isOperator(prevItem) || mathOperatorsPriorities[prevItem] === ZERO) &&
+      isOperator(item) &&
       mathOperators.hasOwnProperty(item);
     const isValidTrigOperatorsPush =
+      isOperator(item) &&
       mathOperatorsPriorities[item] === SECOND &&
-      mathOperators.hasOwnProperty(item) &&
       (key === 0 ||
-        (mathOperators.hasOwnProperty(prevItem) &&
-          mathOperatorsPriorities[prevItem] !== SECOND));
+        (isOperator(prevItem) && mathOperatorsPriorities[prevItem] !== SECOND));
 
     if (isValidNumberPush) {
       result.push(Number(item));