Question

在学习JavaScript并尝试解决挑战性问题时，我的代码不断输出“未定义的值”。

我的代码：

function paidAmount(bill){
var tipPercent
if (bill < 50){
    tipPercent = 0.20;
}
else if (bill >= 50 && bill <=200){
    tipPercent = 0.15;
}
else{
    tipPercent = 0.10;
}
return bill * tipPercent;
}

var tip1 = console.log(paidAmount(124));
var tip2 = console.log(paidAmount(48));
var tip3 = console.log(paidAmount(268));

var tipTotal = [tip1, tip2, tip3];

console.log(tipTotal);

输出：

18.599999999999998
9.600000000000001
26.8
(3) [undefined, undefined, undefined]

Answer 1

您不能分配console.log内部的值。将它们分开

function paidAmount(bill){
var tipPercent
if (bill < 50){
    tipPercent = 0.20;
}
else if (bill >= 50 && bill <=200){
    tipPercent = 0.15;
}
else{
    tipPercent = 0.10;
}
return bill * tipPercent;
}


var tip1 = paidAmount(124);
var tip2 = paidAmount(48);
var tip3 = paidAmount(268);
console.log(paidAmount(124));
console.log(paidAmount(268));
console.log(paidAmount(48));
var tipTotal = [tip1, tip2, tip3];

console.log(tipTotal);

Answer 2

console.log返回未定义。有关更多信息，请参见下面链接的规格。

Namespace Console spec link

Namspace Console spec image

Logger spec

此外，在您的示例中，您不必将结果存储到变量tip1，tip2，tip3中。

相反，您可以直接在console.log中调用paidAmount：

console.log(paidAmount(124), paidAmount(48), paidAmount(268));

Answer 3

[console.log(tip1),console.log(tip2),...]是错误，但是您可以尝试另一种方法：

function paidAmount(bill) {
  var tipTotal = [] ;
  var tipPercent ;

  for (value of bill) {
    tipPercent = (value < 50 ) ? 0.20 : ( ( value >= 50 && value <= 200) ? 0.15 : 0.10 ) ;
    tipTotal.push( value * tipPercent ) ;
  }

  return tipTotal ;
}

console.log( paidAmount([124, 48, 268]) );

Javascript函数/未定义错误-提示计算

3 个答案: