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[英]i want to loop through an array but i dont wanna use for can somebody help me please?
[英]Getting undefined but i would like to use else statement inside for loop and display 'not exist' instead. please help me to fix
我如何在下面使用 else 語句,想將 undefined 替換為“不存在”,嘗試但不起作用。 程序:檢查給定字符串是否包含指定字符的 2 到 4 個數字
function check_char(x, y) { for (var j = 0; j < y.length; j++) { var d = y[j]; } for (var i = 1; i <= 3; i++) { data = x[i] console.log(data) if (data == d) { return d + " exist"; } } } document.write(check_char("Python", "y") + "<br>"); document.write(check_char("JavaScript", "a") + "<br>"); document.write(check_char("Console", "o") + "<br>"); document.write(check_char("Console", "C") + "<br>"); document.write(check_char("Console", "e") + "<br>"); document.write(check_char("JavaScript", "S") + "<br>");
**output:**
y exist
a exist
o exist
undefined
undefined
undefined
嚴格來說,你不需要else
。 記錄字符在字符串中出現的次數。 如果計數 >= 2 和 <= 4 返回“存在”,否則只返回“不存在”。
您應該避免使用document.write
。 此示例有一個額外的 function,它使用從checkChar
function 返回的字符串創建一些 HTML ,然后使用insertAdjacentHML
將其添加到頁面。
function checkChar(str, char) { // Initialise the count let count = 0; // Loop over the string - if the // letter in the iteration is the same as // the character increment the count for (const letter of str) { if (letter === char) ++count; } // If the count is within bounds return "exists" if (count >=2 && count <=4) { return `<span class="red">${char}</span> exists`; } // Otherwise return "does not exist" return `<span class="red">${char}</span> does not exist`; } function write(str) { // Create an HTML paragraph string with the string // returned from `checkChar`, and then add that // to the page const para = `<p>${str}</p>`; document.body.insertAdjacentHTML('beforeend', para); } write(checkChar('Python', 'y')); write(checkChar('JavaScript', 'a')); write(checkChar('Console', 'o')); write(checkChar('Console', 'C')); write(checkChar('Console', 'e')); write(checkChar('JavaScript', 'S'));
.red { color: red; }
嘗試這個,
function check_char(x, y) {
for (var j = 0; j < y.length; j++) {
var d = y[j];
}
for (var i = 1; i <= 3; i++) {
data = x[i]
console.log(data)
if (data == d) {
return d + " exist";
}
}
return 'not exist';
}
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