JS中如何用If else实现多输入值对应同一输出？

Hey there! Great question—you’re right that your current code only handles the "history" case, and we can fix this in a couple of clean, maintainable ways. Let’s break it down:

Option 1: Combine Conditions with Logical OR (||) #

If you only have a small number of trigger values, you can bundle them into a single if statement using the logical OR operator. This keeps things simple for short lists:

<script type="text/javascript">
  var book = "mata"; // Replace with your input value
  // Check if the book matches any math-related keyword
  if (book === "maths" || book === "mathematics" || book === "mata" || book === "maths book") {
    document.write("<b>Maths Book</b>");
  } else if (book === "history") {
    document.write("<b>History Book</b>");
  } else {
    // Optional: Handle unexpected values
    document.write("<b>Unknown Book</b>");
  }
</script>

Pro tip: I used === (strict equality) instead of == here—it’s a JavaScript best practice to avoid weird type coercion bugs.

Option 2: Use an Array with includes() (Better for Scaling) #

If you might add more trigger values later, storing them in an array and using the includes() method is way easier to maintain. No need to chain endless || operators—just update the array:

<script type="text/javascript">
  var book = "mathematics"; // Example input
  // Store all math-related triggers in one array
  const mathBookTriggers = ["maths", "mathematics", "mata", "maths book"];
  
  if (mathBookTriggers.includes(book)) {
    document.write("<b>Maths Book</b>");
  } else if (book === "history") {
    document.write("<b>History Book</b>");
  } else {
    document.write("<b>Unknown Book</b>");
  }
</script>

This approach scales beautifully—if you want to add "math" or "math textbook" later, just drop it into the array and you’re done.

Quick Note on Your Original Code #

Your initial script only checked for the "history" value and had no logic for math-related inputs. By flipping the order (checking math triggers first) and adding the right conditions, we get the behavior you’re looking for.

内容的提问来源于stack exchange，提问作者dentist