Question

function largerNum (a,b){
  if (a>b){
    console.log("The larger number of " +a, "and " +b, "is " +a,".");
  }
  else{
        console.log("The larger number of " +a, "and " +b, "is " +b,".");
  }
}
console.log(largerNum (5,12));

输出显示 - 6和12的较大数字是12 未定义

Answer 1

因为你的函数没有返回，所以console.log(largerNum (5,12))给出了未定义的

让你的函数返回一些东西

chnage to

function largerNum (a,b){
  if (a>b){
    return "The larger number of " + a + " and " + b + " is " + a + "."

  }
  else{
      return "The larger number of " + a + " and " + b + " is " + b + "."

  }
}
console.log(largerNum (5,12));

Answer 2

这是因为该函数没有显式返回任何内容，它默认返回undefined

function largerNum(a, b) {
  if (a > b) {
    console.log("The larger number of " + a, "and " + b, "is " + a, ".");
  } else {
    console.log("The larger number of " + a, "and " + b, "is " + b, ".");
  }
  // this function is not returning anything
}
console.log(largerNum(5, 12));

Answer 3

您没有从largerNum函数返回任何值，因此返回了undefined的默认返回值。您可以像这样重构代码。

注意：该字符串与+连接，而不是使用,将参数分隔为console.log

function largerNum(a, b) {
  if (a > b) {
    return "The larger number of " + a + " and " + b + " is " + a + "."
  }
  else {
    return "The larger number of " + a + " and " + b + " is " + b + "."
  }
}

console.log(
  largerNum(5, 12)
)
console.log(
  largerNum(13, 42)
)

Answer 4

您的larger()函数没有返回任何值，因此您将null传递给最后一个console.log()语句。

function largerNum (a,b){
    if (a>b){
        return a;
    } else {
        return b;
    }
}
console.log(
     "The larger number of " + a + ", and " + b + ", is " + 
      largerNum(a,b) + "."
);

应该工作

Answer 5

因为您在调用函数时不需要console.log：您的函数不返回任何内容，并且您会看到其他undefined。只需从console.log()中删除console.log(largerNum (5,12))包装：

＆＃13;

function largerNum (a,b){
  if (a>b){
    console.log("The larger number of " +a, "and " +b, "is " +a,".");
  }
  else{
    console.log("The larger number of " +a, "and " +b, "is " +b,".");
  }
}
largerNum(5,12);

＆＃13;

或者从函数返回值并记录函数调用：

＆＃13;

function largerNum (a,b){
  if (a>b){
    return "The larger number of " +a+ " and " +b+ " is " +a+ ".";
  }
  else{
    return "The larger number of " +a+ " and " +b+ " is " +b+ ".";
  }
}
console.log(largerNum(5,12));

＆＃13;

scratchpad - 在控制台的输出中继续“未定义”。

5 个答案: