JavaScript/闭包/练习

主题：闭包

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1. 编写一个脚本创建一个可参数化的函数 decoratorFactory。它接受一个字符串，用给定的参数“装饰”日志信息。例如： const tiny = decoratorFactory("日志消息来自子例程 'someTinyAction': "); alert(tiny("除以零。"));。该脚本内部应使用闭包。

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"use strict";

function decoratorFactory(someText) {
  // 'someText' is known in 'decoratorFunction' as well as in 'logFunction'
  const logFunction = function (message) {
    // use 'someText' from the outer lexical environment and the function's parameter 'message'
    return(someText + ": " + message) // maybe: plus timestamp, ...
  }
  return logFunction;
}

const computeMsg = decoratorFactory("Log message from subroutine 'computeAverage'");
alert(computeMsg("Division by zero."));

const main = decoratorFactory("*** Log message from 'main'");
alert(main("No database connection."));

alert(main("Unknown system error."));