I am trying to access a method called status inside a nested function.

class Logger {
  #status = false;
  constructor(){
    console=(function(oldCons){
      return {
        log:function(text){
          if(this.status()){
            var e = new Error();
            if(!e.stack){
              try { throw e; } catch (e) { if(!e.stack){} }
            }
            var stack = e.stack.toString().split(/\r\n|\n/);
            for(var [key, step] of Object.entries(stack)){ stack[key] = step.trim(); }
            if(text === ''){ text = '""'; }
            var timeElapsed = Date.now();
            var now = new Date(timeElapsed);
            var day = String(now.getDate()).padStart(2, '0');
            var month = String(now.getMonth()   1).padStart(2, '0');
            var year = now.getFullYear();
            var hours = String(now.getHours()).padStart(2, '0');
            var minutes = String(now.getMinutes()).padStart(2, '0');
            var secondes = String(now.getSeconds()).padStart(2, '0');
            var date = year '-' month '-' day ' ' hours ':' minutes ':' secondes;
            oldCons.log('[' date ']',text);oldCons.log(stack);
          }
        },
        info:function(text){ oldCons.info(text); },
        warn:function(text){ oldCons.warn(text); },
        error:function(text){ if(this.status()){ oldCons.error(text); } }
      };
    }(window.console));
    window.console = console;
    }
  status(){ return this.#status; }
  enable(){ this.#status = true; }
  disable(){ this.#status = false; }
  toggle(status = null){
    if(status == null){
      if(this.#status){ this.disable(); } else { this.enable(); }
    } else { this.#status = status; }
  }
}

const Log = new Logger();

But I end up with an error : Uncaught TypeError: this.status is not a function. I understand that this usually refer to the current function. How can I access the status method in the 2 instance inside the functions in the constructor?

CodePudding user response：

this does not point to the Logger instance in this case it points to the log property of your return object. You can use a reference to this, like in the following example self:

class Logger {
  #status = false;
  constructor() {
    const self = this;

    console = (function(oldCons) {
      return {
        log: function(text) {
          if (self.status()) {
            var e = new Error();
            if (!e.stack) {
              try {
                throw e;
              } catch (e) {
                if (!e.stack) {}
              }
            }
            var stack = e.stack.toString().split(/\r\n|\n/);
            for (var [key, step] of Object.entries(stack)) {
              stack[key] = step.trim();
            }
            if (text === '') {
              text = '""';
            }
            var timeElapsed = Date.now();
            var now = new Date(timeElapsed);
            var day = String(now.getDate()).padStart(2, '0');
            var month = String(now.getMonth()   1).padStart(2, '0');
            var year = now.getFullYear();
            var hours = String(now.getHours()).padStart(2, '0');
            var minutes = String(now.getMinutes()).padStart(2, '0');
            var secondes = String(now.getSeconds()).padStart(2, '0');
            var date = year   '-'   month   '-'   day   ' '   hours   ':'   minutes   ':'   secondes;
            oldCons.log('['   date   ']', text);
            oldCons.log(stack);
          }
        },
        info: function(text) {
          oldCons.info(text);
        },
        warn: function(text) {
          oldCons.warn(text);
        },
        error: function(text) {
          if (this.status()) {
            oldCons.error(text);
          }
        }
      };
    }(window.console));
    window.console = console;
  }
  status() {
    return this.#status;
  }
  enable() {
    this.#status = true;
  }
  disable() {
    this.#status = false;
  }
  toggle(status = null) {
    if (status == null) {
      if (this.#status) {
        this.disable();
      } else {
        this.enable();
      }
    } else {
      this.#status = status;
    }
  }
}

const Log = new Logger();