JavaScript switch-case 内部结构

Question

考虑以下代码:

// Checking parities
switch(queueingSystem.Priority) {
    case 1: 
         FetchGridElements();
         break;
    case 1: 
         BindToControls(this, document.getElementsByClassName("grid-controls"));
         break;
    default:
         return false;
}

JavaScript 是否在内部测试每个case 的值和类型，等同于:

queueingSystem.Priority === 1

或者

queueingSystem.Priority == 1

Answer 1

它检查严格相等 === 如下代码所示:

switch (1) {
  case "1":
     console.log('ok');
     break;
  default :
     console.log('nok');
}

记录 nok。

它在 the ECMAScript specification 中定义:

If input is equal to clauseSelector as defined by the === operator, then