javascript - 尝试通过输入查找数组中是否存在数字

Question

我试图通过使用输入在数组中搜索来查找数字。知道为什么这不起作用吗？

每次运行代码时，我只会收到消息:

"Number does not exist"

var arr = [18, 21, 34, 42, 65, 63, 39, 13, 15, 24, -1, 14, 15];

var number = document.getElementById("find").value;

var svar = "";

function exists(){

    for(i=0; i < arr.length; i++){
         if(parseInt(arr[i]) == parseInt(number)){
              svar++;
              document.getElementById("existsArray").innerHTML = tall + "Number exists";

         } else {
              document.getElementById("existsArray").innerHTML = tall + "Number does not exist";       
         }
     }
 }

<p id="existsArray"></p>
<input placeholder="what number would you like to find?" id="find" type="number">
<button type="button" onclick="exists()">Finn tallet</button>

Answer 1

我用 indexOf 替换了你的 for 循环

如果您仍然想使用循环，则应该在找到匹配的数字时中断

var arr = [18, 21, 34, 42, 65, 63, 39, 13, 15, 24, -1, 14, 15];
var svar = 0;

function exists() {
  var number = +document.getElementById("find").value;
  if (arr.indexOf(number) !== -1) {
    svar++;
    document.getElementById("existsArray").innerHTML = "Number exists";
  } else {
    document.getElementById("existsArray").innerHTML = "Number does not exist";
  }
}

<input type="number" id="find" />
<button onclick="exists();">Does it exist ?</button>
<p id="existsArray"></p>

如果你想获得出现的次数，你应该使用这个:

var occurrences = arr.filter(function (num) {return num === number;}).length