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javascript/examples/1_3_functions.js

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+"use strict";
+
+chapter("Functions");
+section("Arguments");
+
+subsection("Indices");
+let dumpArgs = function() {
+    println(arguments.constructor.name);
+    for (let i = 0; i < arguments.length; i++) {
+        println("   ", i, arguments[i]);
+    }
+};
+println("let dumpArgs =", dumpArgs);
+example("dumpArgs(1, 2, 'hello', null, undefined)");
+
+
+subsection("Values");
+let dumpArgs2 = function() {
+    println(arguments.constructor.name);
+    for (const arg of arguments) {
+        println("   ", arg);
+    }
+};
+println("let dumpArgs2 =", dumpArgs2);
+example("dumpArgs2(1, 2, 'hello', null, undefined)");
+
+
+subsection("sum");
+
+let sum = function() {
+    let result = 0;
+    for (const arg of arguments) {
+        result += arg;
+    }
+    return result;
+};
+println("let sum =", sum);
+example("sum(1, 2, 3)");
+
+
+subsection("minimum");
+
+let minimum = function() {
+    let result = Infinity;
+    for (const arg of arguments) {
+        if (result > arg) {
+            result = arg;
+        }
+    }
+    return result;
+};
+println("let minimum =", minimum);
+example("minimum(1, -2, 3)");
+
+
+section("Named functions and arguments");
+
+function min(a, b) {
+    //println("   ", typeof(a), typeof(b));
+    return a < b ? a : b;
+}
+println(min);
+example("min(1, -1)");
+example("min(1, -1)");
+example("min(1)");
+example("min()");
+
+subsection("Still values");
+let m = min;
+example("m");
+example("m.name");
+example("m.length");
+example("m(10, 20)");
+
+
+section("Default arguments");
+
+function def(a = -10, b = -20) {
+    return [a, b];
+}
+println(def);
+example("def(1, 2)");
+example("def(1)");
+example("def()");
+
+
+section("Rest argument and spread calls");
+
+function minRest(first, ...rest) {
+    let result = first;
+    for (const a of rest) {
+        result = min(result, a);
+    }
+    return result;
+}
+println(minRest);
+example("minRest(1)");
+example("minRest(1, -1)");
+example("minRest(1, -1, 2, -2)");
+example("minRest(...[1, -1, 2, -2])");
+example("minRest(1, -1, ...[2, -2])");
+
+
+section("Arrow functions");
+
+const minArr = (a, b) => a < b ? a : b;
+example("minArr");
+example("minArr(1, -2)");
+
+const minArrow = (first, ...rest) => {
+    let result = first;
+    for (const a of rest) {
+        result = Math.min(result, a);
+    }
+    return result;
+};
+example("minArrow");
+example("minArrow(1)");
+example("minArrow(1, -1)");
+example("minArrow(1, -1, 2, -2)");
+
+const stupidArrow = (v) => {
+    println(v);
+    // No "arguments" for arrow functions
+    // println(arguments);
+};
+example("stupidArrow");
+example("stupidArrow(3)");