Javascript 为什么真值或假值在角度控制器中不起作用？

我有点困惑，在角度上如何评估真实值或虚假值。显然，当我直接在角上做以下事情时。。。事情是这样的

if (0) { console.log('not printed'); }
else { console.log('printed'); }

if (1) { console.log('printed'); }
else { console.log('not printed'); }

但是，如果我从模板向控制器传递一个值。。。然后事情就不起作用了。为什么?

function (someValue) {

    if (someValue) { console.log('always printed  whether someValue is 0 or 1'); }
    else { console.log('not printed'); }

...

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比较起来，js中有松散相等和严格相等。如果该值不是布尔类型，则将转换为true或false

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通常，我使用全局函数来推导真实值

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您确定someValue不是字符串0吗？是的，它是字符串！好吧，我明白了。所以这毕竟与角度无关。。。。常规javascript也会有相同的结果？在javascript中使用0和1表示true和false非常容易出错。是的！！例如，控制台中的0提供了true。是的，常规JS也会有相同的效果。0与0不同/为空/未定义。

if (someValue === '0' || someValue === '1') { 
  console.log('always printed  whether someValue is 0 or 1'); 
}
else { 
  console.log('not printed'); 
}

function truthy(val){
  switch(typeof val){
    case "number":
      // since the val is already a number, only zero and NaN should be counted as falsy.
      return val !== 0 && !Number.isNaN(Number(val));
    case "string":
      // val is string, so need to check if its empty or "0". Otherwise it should be counted as truthy
      return val !== "" && val !== "0";
    case "boolean":
      // val is already boolean so only boolean check would suffice
      return val === true;
    case "symbol":
      //    symbol should be truthy
      return true;
    case "object":
      // object can be deceiving, so lets check for NULL and empty object

      if( val === null ){
        return false;
      }
      else{
        for( var i in val ){
          if( val.hasOwnProperty(i) ){
            return true;
          }
        }
      }

      return false;

    case "undefiend":
      return false;
    case "function":
      return true;
  }
}
function falsy(val){
  return !truthy(val);
}

console.log(truthy(1));     // should be true
console.log(truthy(0));     // should be false
console.log(truthy(NaN));   // should be false
console.log(truthy(""));    // should be false
console.log(truthy("0"));   // should be false
console.log(truthy("1"));   // should be true
console.log(truthy("meh")); // should be true
console.log(truthy({}));    // should be false
console.log(truthy(null));  // should be false
console.log(truthy(false)); // should be false