revision new files

Chapter 12/promises.js

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+let promise = new Promise(function (resolve, reject) {
+    // do something that might take a while
+    // let's just set x instead for this example  
+    let x = 20;
+    if (x > 10) {
+        resolve(x); // on success
+    } else {
+        reject("Too low");  // on error
+    }
+});
+
+promise.then(
+    function (value) {
+        console.log("Success:", value)
+    },
+    function (error) {
+        console.log("Error:", error)
+    }
+);