我正在尝试做一个阶乘计算器。如何检查输入是否为空？我尝试过“空”。但它不起作用或者我无法正确使用它。
抱歉这个愚蠢的问题。我是新手JavaScript
function myFriday() {
var input = document.getElementById("input1").value;
var ever = function () {
if( !(isNaN(input))) {
var result = 1;
for(var i = 1; i <= input; i++ ) {
result = result * i
}
return result;
}
else if (input == null){
return "Please input a number"
}
else{
return "Please input a number"
}
}
document.getElementById("input2").value = ever();
}
<p>Input: <input type="text" id = "input1" /></p>
<p>Input: <input type="text" id = "input2" /></p>
<button onclick = "myFriday()">Calculate</button>
<p >RESULT: <span id = "result" style = "color:red"></span> </p>
function myFriday() {
var input = document.getElementById("input1").value;
var ever = function() {
if (input.trim() == '') {
return "Please input a number"
} else if (!(isNaN(input))) {
var result = 1;
for (var i = 1; i <= input; i++) {
result = result * i
}
return result;
}
}
document.getElementById("input2").value = ever();
}
<p>Input:
<input type="text" id="input1" />
</p>
<p>Input:
<input type="text" id="input2" />
</p>
<button onclick="myFriday()">Calculate</button>
<p>RESULT: <span id="result" style="color:red"></span>
</p>
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