5.8 object functions

5.8objectkeys/t.js

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+
+console.log("====================object.keys, values, entries====================")
+
+console.log("Object function, you must call Object.keys but not obj.keys")
+console.log("Object.keys(obj) - returns an array of keys")
+console.log("Object.values(obj) - returns an array of values")
+console.log("Object.entries(obj) - returns an array of [key, value] pair")
+console.log("Object.fromEntries(array) - on the resulting array to turn it back into an object")
+
+let prices = {
+    banana : 4,
+    orange : 2,
+    meat : 1,
+}
+console.log(`Object.entries(prices): ${Object.entries(prices)}`)
+
+let doubleprices = Object.fromEntries(
+    Object.entries(prices).map(entry => [entry[0], entry[1] * 2])
+);
+console.log(`Object.entries(doubleprices): ${Object.entries(doubleprices)}`)
+
+Object.values(prices).reduce((sum, cur)=> sum+cur, 0)
+
+function sumSalaries(salaries ){
+    return Object.values(salaries).reduce((sum, cur) => sum + cur, 0);
+}
+
+let salaries = {
+    "John": 100,
+    "Pete": 300,
+    "Mary": 250
+};
+
+console.log(sumSalaries(salaries));
+
+function count(user){
+    return Object.keys(user).length;
+}
+
+let user = {
+    name : "John",
+    age: 30
+};
+console.log(count(user));