Javascript if 语句未按预期工作

Question

我正在尝试创建一个带有分数的小型调查。我想让它一旦用户达到分数“4”，它就会提醒一些消息。我为它编写了 if 语句，但由于某种原因它从不发出警报。但如果我手动将分数变量更改为 4，一切都会按预期进行。

我哪里出错了？

代码如下:

http://jsfiddle.net/uy9kq9mx/

<script>
var score = 0;

function checkQuestionOne (){

    var jautViens = document.getElementById('jaut1Pirm');
    var jautDivi = document.getElementById('Jaut1Otra');
    var jautTris = document.getElementById('Jaut1Tres');
    var jautCetri = document.getElementById('Jaut1Cetu');

    if(jautViens.checked) {
        alert(++score)
    }else if(jautDivi.checked || jautTris.checked || jautCetri.checked) {
        alert("Nepareizi")
    }else{
        alert("Izvēlies opciju!")
    }
}

if (score == 4){
    alert(score);

}else{

}

Answer 1

您需要检查该函数的条件

var score = 0;

function checkQuestionOne() {

    var jautViens = document.getElementById('jaut1Pirm');
    var jautDivi = document.getElementById('Jaut1Otra');
    var jautTris = document.getElementById('Jaut1Tres');
    var jautCetri = document.getElementById('Jaut1Cetu');

    if (jautViens.checked) {
        ++score;
        //since value of score is changed only in this block you can place the if block here
        if (score == 4) {
            alert('score is 4');
        }
    } else if (jautDivi.checked || jautTris.checked || jautCetri.checked) {
        alert("Nepareizi")
    } else {
        alert("Izvēlies opciju!")
    }
    
    //keep the if block here, if there are multiple blocks in which the value of score is changed
}

<h1>Pirmais jautājums (1. pareizā)</h1>
<input type="radio" name="jaut1" id="jaut1Pirm" value="pirma" />Šī ir pirmā atbilde
<br/>
<input type="radio" name="jaut1" id="Jaut1Otra" value="otra" />Šī ir otrā atbilde
<br/>
<input type="radio" name="jaut1" id="Jaut1Tres" value="tresa" />Šī ir trešā atbilde
<br/>
<input type="radio" name="jaut1" id="Jaut1Cetu" value="ceturta" />Šī ir ceturtā atbilde
<br/>
<br/>
<button type="submit" onclick="checkQuestionOne();">Spied</button>

当您将其保留在函数之外时，if 条件仅计算一次，但每次 score 的值发生更改时您都需要检查它。