cute · April 26, 2019 22:59 · Oct 4, 2018 · Oct 4, 2018
diff --git a/JavaScriptCore+fetch.swift b/JavaScriptCore+fetch.swift
@@ -0,0 +1,145 @@
+import JavaScriptCore
+
+extension JSContext {
+    subscript(key: String) -> Any {
+        get {
+            return self.objectForKeyedSubscript(key)
+        }
+        set{
+            self.setObject(newValue, forKeyedSubscript: key as NSCopying & NSObjectProtocol)
+        }
+    }
+}
+
+@objc protocol JSConsoleExports: JSExport {
+    static func log(_ msg: String)
+}
+
+class JSConsole: NSObject, JSConsoleExports {
+    class func log(_ msg: String) {
+        print(msg)
+    }
+}
+
+@objc protocol JSPromiseExports: JSExport {
+    func then(_ resolve: JSValue) -> JSPromise?
+    func `catch`(_ reject: JSValue) -> JSPromise?
+}
+
+class JSPromise: NSObject, JSPromiseExports {
+    var resolve: JSValue?
+    var reject: JSValue?
+    var next: JSPromise?
+    var timer: Timer?
+
+    func then(_ resolve: JSValue) -> JSPromise? {
+        self.resolve = resolve
+
+        self.next = JSPromise()
+
+        self.timer?.fireDate = Date(timeInterval: 1, since: Date())
+        self.next?.timer = self.timer
+        self.timer = nil
+
+        return self.next
+    }
+
+    func `catch`(_ reject: JSValue) -> JSPromise? {
+        self.reject = reject
+
+        self.next = JSPromise()
+
+        self.timer?.fireDate = Date(timeInterval: 1, since: Date())
+        self.next?.timer = self.timer
+        self.timer = nil
+
+        return self.next
+    }
+
+    func fail(error: String) {
+        if let reject = reject {
+            reject.call(withArguments: [error])
+        } else if let next = next {
+            next.fail(error: error)
+        }
+    }
+
+    func success(value: Any?) {
+        guard let resolve = resolve else { return }
+        var result:JSValue?
+        if let value = value  {
+            result = resolve.call(withArguments: [value])
+        } else {
+            result = resolve.call(withArguments: [])
+        }
+
+        guard let next = next else { return }
+        if let result = result {
+            if result.isUndefined {
+                next.success(value: nil)
+                return
+            } else if (result.hasProperty("isError")) {
+                next.fail(error: result.toString())
+                return
+            }
+        }
+
+        next.success(value: result)
+    }
+}
+
+extension JSContext {
+    static var plus:JSContext? {
+        let jsMachine = JSVirtualMachine()
+        guard let jsContext = JSContext(virtualMachine: jsMachine) else {
+            return nil
+        }
+
+        jsContext.evaluateScript("""
+            Error.prototype.isError = () => {return true}
+        """)
+        jsContext["console"] = JSConsole.self
+        jsContext["Promise"] = JSPromise.self
+
+        let fetch:@convention(block) (String)->JSPromise? = { link in
+            let promise = JSPromise()
+            promise.timer = Timer.scheduledTimer(withTimeInterval: 1, repeats: false) {timer in
+                timer.invalidate()
+
+                if let url = URL(string: link) {
+                    URLSession.shared.dataTask(with: url){ (data, response, error) in
+                        if let error = error {
+                            promise.fail(error: error.localizedDescription)
+                        } else if
+                            let data = data,
+                            let string = String(data: data, encoding: String.Encoding.utf8) {
+                            promise.success(value: string)
+                        } else {
+                            promise.fail(error: "\(url) is empty")
+                        }
+                        }.resume()
+                } else {
+                    promise.fail(error: "\(link) is not url")
+                }
+            }
+
+            return promise
+        }
+        jsContext["fetch"] = unsafeBitCast(fetch, to: JSValue.self)
+
+        return jsContext
+    }
+}
+
+guard let jsContext = JSContext.plus else {exit(-1)}
+jsContext.exceptionHandler = { context, exception in
+    print("JS Error: \(String(describing: exception))")
+}
+
+jsContext.evaluateScript("""
+fetch("https://github.com")
+.then(data=>{
+    console.log(data)
+})
+.catch(e=>console.log(e))
+""")