xcode JavaScriptCore console.log
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JavaScriptCore console.log
提问by SheetJS
I've put together a very simple program that uses JavaScriptCore to evaluate JS:
我已经编写了一个非常简单的程序，它使用 JavaScriptCore 来评估 JS：
#import <CoreFoundation/CoreFoundation.h>
#import <JavaScriptCore/JavaScriptCore.h>
int main(int argc, const char * argv[])
{
JSGlobalContextRef ctx = JSGlobalContextCreate(NULL);
FILE *f = fopen(argv[1],"r");
char * buffer = malloc(10000000);
fread(buffer,1,10000000,f);
CFStringRef strs = CFStringCreateWithCString(NULL, buffer, kCFStringEncodingASCII);
JSStringRef jsstr = JSStringCreateWithCFString(strs);
JSValueRef result = JSEvaluateScript(ctx, jsstr, NULL, NULL, 0, NULL);
double res = JSValueToNumber(ctx, result, NULL);
JSGlobalContextRelease(ctx);
printf("%lf\n", res);
return 0;
}
The idea here is that the last value is expected to be a Number, and that value is printed. This works for valid javascript code, such as
这里的想法是最后一个值应该是 a Number，然后打印该值。这适用于有效的 javascript 代码，例如
var square = function(x) { return x*x; }; square(4)
However, if the code tries to perform a console.log, the program segfaults. Is there a log function available in JSC or do I have to roll my own?
但是，如果代码尝试执行 a console.log，则程序会出现段错误。JSC 中是否有可用的日志功能，还是我必须自己推出？
采纳答案by Mike
You do have to provide your own console log if using the JavaScriptCore framework from Mac or IOS.
如果使用 Mac 或 IOS 的 JavaScriptCore 框架，则必须提供自己的控制台日志。
Here is some code that worked for me (sorry it is Objective-C rather than standard C as per your code above):
这是一些对我有用的代码（抱歉，按照上面的代码，它是 Objective-C 而不是标准 C）：
JSContext *javascriptContext = [[JSContext alloc] init];
javascriptContext[@"consoleLog"] = ^(NSString *message) {
NSLog(@"Javascript log: %@",message);
};
Then you use it from Javascript by:
然后您通过以下方式从 Javascript 中使用它：
consoleLog("My debug message");
Note that I have tried to define a vararg version (log taking multiple parameters) but I couldn't get this to work correctly across the framework api.
请注意，我试图定义一个可变参数版本（日志采用多个参数），但我无法让它在框架 api 中正常工作。
Note that this solution uses features introduced with the new Objective-C API for the JavaScriptCore.framework introduced at the same time as IOS 7. If you are looking for an intro to this well-integrated bridge between Objective-C and Javascript, check out the 2013 WWDC introduction "Integrating JavaScript into Native Apps" session on Apple's developer network: https://developer.apple.com/videos/wwdc/2013/?id=615
请注意，此解决方案使用了与 IOS 7 同时引入的 JavaScriptCore.framework 的新 Objective-C API 引入的功能。如果您正在寻找有关 Objective-C 和 Javascript 之间良好集成桥梁的介绍，请查看Apple 开发者网络上的 2013 年 WWDC 介绍“将 JavaScript 集成到本机应用程序”会议：https: //developer.apple.com/videos/wwdc/2013/?id=615
Update to answer:
更新回答：
For those of you wanting to maximise your javascript code reuse without refactoring, I've managed to get a version working that declares a log of the form console.log():
对于那些希望在不重构的情况下最大限度地重用 javascript 代码的人，我设法使一个版本可以正常工作，该版本声明了表单console.log()的日志：
JSContext *javascriptContext = [[JSContext alloc] init];
[javascriptContext evaluateScript:@"var console = {}"];
javascriptContext[@"console"][@"log"] = ^(NSString *message) {
NSLog(@"Javascript log: %@",message);
};
Then you use it from Javascript by:
然后您通过以下方式从 Javascript 中使用它：
console.log("My debug message");
回答by AlBeebe
Swift 3.0
斯威夫特 3.0
let javascriptContext = JSContext()
javascriptContext?.evaluateScript("var console = { log: function(message) { _consoleLog(message) } }")
let consoleLog: @convention(block) (String) -> Void = { message in
print("console.log: " + message)
}
javascriptContext?.setObject(unsafeBitCast(consoleLog, to: AnyObject.self), forKeyedSubscript: "_consoleLog" as (NSCopying & NSObjectProtocol)!)
Swift 2.1
斯威夫特 2.1
let javascriptContext = JSContext()
javascriptContext.evaluateScript("var console = { log: function(message) { _consoleLog(message) } }")
let consoleLog: @convention(block) String -> Void = { message in
print("console.log: " + message)
}
javascriptContext.setObject(unsafeBitCast(consoleLog, AnyObject.self), forKeyedSubscript: "_consoleLog")
Then you use it from Javascript by:
然后您通过以下方式从 Javascript 中使用它：
console.log("My debug message");
回答by Anton Belousov
self.jsContext = JSContext()
self.jsContext.evaluateScript(...)
let logFunction: @convention(block) (String) -> Void = { (string: String) in
print(string)
}
self.jsContext.setObject(logFunction, forKeyedSubscript: "consoleLog" as NSCopying & NSObjectProtocol)
回答by Rakesh Yembaram
You can debug JS file attached to context in Safari.
您可以在 Safari 中调试附加到上下文的 JS 文件。
Steps:
脚步：
1) Start Safari
1) 启动 Safari
2) In Safari, enable the Develop menu by going to "Preferences" -> "Advanced" -> "Show Develop menu in menu bar"
2) 在 Safari 中，通过转到“首选项”->“高级”->“在菜单栏中显示开发菜单”启用开发菜单
3) Go to Develop menu -> "Simulator" or name of your computer -> select "Automatically show web inspector for JSContexts" and "Automatically pause connecting to JSContexts"
3) 转到开发菜单 -> “模拟器”或您的计算机名称 -> 选择“自动显示 JSContexts 的 Web 检查器”和“自动暂停连接到 JSContexts”
4) Re-run your project and Safari should auto-show the web inspector
4) 重新运行你的项目，Safari 应该会自动显示 web 检查器
