意外的標識 - 常量

Question

我學習的node.js，我有例子問題：

"use strict"; 

// Create a new globetrotter! 
const globetrotter = { 
    // Language spoken in the country our globetrotter is currently in 
    const current_lang = undefined, 

    // Number of countries our globetrotter has travelled to 
    let countries = 0, 

    // See how many countries we've travelled to 
    get countryCount() { 
     return this.countries; 
    }, 

    // Reset current language whenever our globe trotter flies somewhere new 
    set languages (language) { 
     // Increment number of coutnries our globetrotter has travelled to 
     countries += 1; 

     // Reset current language 
     this.current_lang = language; 
    }; 
}; 

globetrotter.language = 'Japanese'; 
globetrotter.countryCount; // 1 

globetrotter.language = 'Spanish'; 
globetrotter.countryCount; // 2 

這回我的錯誤：

index.js:6 
    const current_lang = undefined, 
      ^^^^^^^^^^^^ 

SyntaxError: Unexpected identifier 

爲什麼以及如何解決這個問題？

我在版本8.1.0中有node.js。

Answer 1

您正在定義對象文本內部的變量，這是不正確的對象的JavaScript語法。 https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Working_with_Objects