爲什麼我的while循環沒有逃脫？ （JavaScript）的

Question

做練習，我想不通爲什麼我的while循環不逃避，它口口聲聲說的值是無效的，即使是隻輸入數字。有任何想法嗎？

// 31. Karvonen Heart Rate 
 
var age, restingPulse, targetRate, numCheckAge, numCheckPulse, valid; 
 
    
 
    valid = false; 
 
    numCheckAge = /^\d+$/.test(age); 
 
    numCheckPulse = /^\d+$/.test(restingPulse); 
 
    
 
    while(valid === false) { 
 
     age = parseFloat(prompt("Enter your age:")); 
 
     restingPulse = parseFloat(prompt("Enter your resting heart rate:")); 
 
     if(numCheckAge === true && numCheckPulse === true) { 
 
     valid = true; 
 
     } else { 
 
     alert("Sorry. That's not a valid input, please enter numbers."); 
 
     } 
 
    } 
 
    
 
    for (var i = 0.55; i < 1; i+=0.05){ 
 
     targetRate = (((220 - age) - restingPulse) * i) + restingPulse; 
 
     document.write("Intensity: " + Math.round((i * 100)) + "% | Rate: " + Math.round(targetRate) + "<br>"); 
 
    }

Answer 1

我已經簡化和flexified你的代碼;）

檢查了這一點：

 
 
function requireNumericPrompt(text) { 
 
    var value; 
 
    while(true) { 
 
    if(/^\d+$/.test(value = prompt(text))) { 
 
     return value; 
 
    } 
 
    alert("Sorry. Please enter valid (numeric) value."); 
 
    } 
 
} 
 

 
var age = parseInt(requireNumericPrompt("Enter your age:")); 
 
var restingPulse = parseInt(requireNumericPrompt("Enter your resting heart rate:")); 
 

 
document.write('Age: ' + age + '<br/>'); 
 
document.write('Resting pulse: ' + restingPulse + '<br/>'); 
 
for (var targetRate, i = 0.55; i < 1; i+=0.05){ 
 
    targetRate = (((220 - age) - restingPulse) * i) + restingPulse; 
 
    document.write("Intensity: " + Math.round((i * 100)) + "% | Rate: " + Math.round(targetRate) + "<br>"); 
 
}

Answer 2

在哪里哪里，你測試正則表達式的點，這些變量age和restingPulse是undefined。你必須在循環中進行測試的代碼移到，後這些變量已收到來自用戶的輸入值：

while(!valid) { 
    age = parseFloat(prompt("Enter your age:")); 
    restingPulse = parseFloat(prompt("Enter your resting heart rate:")); 

    numCheckAge = /^\d+$/.test(age); 
    numCheckPulse = /^\d+$/.test(restingPulse); 
    if(numCheckAge && numCheckPulse) { 
    valid = true; 
    } 
    else { 
    alert("Sorry. That's not a valid input, please enter numbers."); 
    } 
} 

此外，您還可以刪除=== true位，使用的真值變量直接用於測試。

Answer 3

var age, restingPulse, targetRate, numCheckAge, numCheckPulse, valid; 
 

 
valid = false; 
 
numCheckAge =function(a) { 
 
\t return /^\d+$/.test(a); 
 
} 
 
numCheckPulse = function(a){ 
 
return /^\d+$/.test(restingPulse); 
 
} 
 

 
while(valid === false) { 
 
    age = parseFloat(prompt("Enter your age:")); 
 
    restingPulse = parseFloat(prompt("Enter your resting heart rate:")); 
 
    if(numCheckAge(age) && numCheckPulse(restingPulse)) { 
 
    valid = true; 
 
    } else { 
 
    alert("Sorry. That's not a valid input, please enter numbers."); 
 
    } 
 
} 
 

 
for (var i = 0.55; i < 1; i+=0.05){ 
 
    targetRate = (((220 - age) - restingPulse) * i) + restingPulse; 
 
    document.write("Intensity: " + Math.round((i * 100)) + "% | Rate: " + Math.round(targetRate) + "<br>"); 
 
}

你需要便利着想將你的檢查代碼改爲一個函數，而不是一個變量。

Answer 4

你在正確的軌道，你剛纔忘了初始化變量上。

var age, restingPulse, targetRate, numCheckAge, numCheckPulse, valid; 
 

 
age = 0; 
 
restingPulse = 0; 
 

 
valid = false; 
 
numCheckAge = /^\d+$/.test(age); 
 
numCheckPulse = /^\d+$/.test(restingPulse); 
 

 
while(valid !== true) { 
 
    age = parseFloat(prompt("Enter your age:")); 
 
    restingPulse = parseFloat(prompt("Enter your resting heart rate:")); 
 
    if(numCheckAge === true && numCheckPulse === true) { 
 
     valid = true; 
 
    } else { 
 
     alert("Sorry. That's not a valid input, please enter numbers."); 
 
    } 
 
} 
 

 
for (var i = 0.55; i < 1; i+=0.05){ 
 
    targetRate = (((220 - age) - restingPulse) * i) + restingPulse; 
 
    document.write("Intensity: " + Math.round((i * 100)) + "% | Rate: " + Math.round(targetRate) + "<br>"); 
 
}