關於jq的delegate問題

//PHP
Categories
    ";    if(mysqli_num_rows($run_query)>0){                while($row = mysqli_fetch_array($run_query)){            $cid = $row["cat_id"];            $cat_name = $row["cat_title"];//問題在這裡            echo "
$cat_name
            ";        }        echo "";    }}if(isset($_POST["brand"])){    $brand_query = "SELECT * FROM brands";    $run_query = mysqli_query($con,$brand_query);    echo "    
Brands
    ";    if(mysqli_num_rows($run_query)>0){        while($row = mysqli_fetch_array($run_query)){            $bid = $row["brand_id"];            $brand_name = $row["brand_title"];            echo "
$brand_name
            ";        }        echo "";    }}if(isset($_POST["getProduct"])){    $product_query =  "SELECT * FROM products ORDER BY RAND() LIMIT 0,9";    $run_query = mysqli_query($con,$product_query);    if(mysqli_num_rows($run_query) >0 ){        while($row = mysqli_fetch_array($run_query)){           $pro_id = $row['product_id'];           $pro_cat = $row['product_cat'];           $pro_brand = $row['product_brand'];           $pro_title = $row['product_title'];           $pro_price = $row['product_price'];           $pro_image = $row['product_image'];           echo "                                                                 $pro_title                                                                                                                    $.$pro_price.00                              AddToCart                                                                                       ";        }    }}?>

//JS $(document).ready(function() {    cat();    brand();    product();    function cat() {        $.ajax({                url: 'action.php',                type: 'POST',                data: {                    category: 1                },            })            .done(function(data) {                //console.log(data);                $("#get_category").html(data);            });    }    function brand() {        $.ajax({                url: 'action.php',                type: 'POST',                data: {                    brand: 1                },            })            .done(function(data) {                //console.log(data);                $("#get_brand").html(data);            });    }    function product() {        $.ajax({                url: 'action.php',                type: 'POST',                data: {                    getProduct: 1                },            })            .done(function(data) {                //console.log(data);                $("#get_product").html(data);            });    }    //使用 delegate() 方法。on不能擷取    $("body").delegate(".category", "click", function() {        alert(123);    })    // $(".category").on("click", function(event) {    //     alert(13);    // });})

我用on的方法為什麼點擊沒反應？而delegate卻有？是不是因為這個class寫在php上，on不能讀取？還是怎麼樣？

回複內容：

//PHP
Categories
    ";    if(mysqli_num_rows($run_query)>0){                while($row = mysqli_fetch_array($run_query)){            $cid = $row["cat_id"];            $cat_name = $row["cat_title"];//問題在這裡            echo "
$cat_name
            ";        }        echo "";    }}if(isset($_POST["brand"])){    $brand_query = "SELECT * FROM brands";    $run_query = mysqli_query($con,$brand_query);    echo "    
Brands
    ";    if(mysqli_num_rows($run_query)>0){        while($row = mysqli_fetch_array($run_query)){            $bid = $row["brand_id"];            $brand_name = $row["brand_title"];            echo "
$brand_name
            ";        }        echo "";    }}if(isset($_POST["getProduct"])){    $product_query =  "SELECT * FROM products ORDER BY RAND() LIMIT 0,9";    $run_query = mysqli_query($con,$product_query);    if(mysqli_num_rows($run_query) >0 ){        while($row = mysqli_fetch_array($run_query)){           $pro_id = $row['product_id'];           $pro_cat = $row['product_cat'];           $pro_brand = $row['product_brand'];           $pro_title = $row['product_title'];           $pro_price = $row['product_price'];           $pro_image = $row['product_image'];           echo "                                                                 $pro_title                                                                                                                    $.$pro_price.00                              AddToCart                                                                                       ";        }    }}?>

//JS $(document).ready(function() {    cat();    brand();    product();    function cat() {        $.ajax({                url: 'action.php',                type: 'POST',                data: {                    category: 1                },            })            .done(function(data) {                //console.log(data);                $("#get_category").html(data);            });    }    function brand() {        $.ajax({                url: 'action.php',                type: 'POST',                data: {                    brand: 1                },            })            .done(function(data) {                //console.log(data);                $("#get_brand").html(data);            });    }    function product() {        $.ajax({                url: 'action.php',                type: 'POST',                data: {                    getProduct: 1                },            })            .done(function(data) {                //console.log(data);                $("#get_product").html(data);            });    }    //使用 delegate() 方法。on不能擷取    $("body").delegate(".category", "click", function() {        alert(123);    })    // $(".category").on("click", function(event) {    //     alert(13);    // });})

我用on的方法為什麼點擊沒反應？而delegate卻有？是不是因為這個class寫在php上，on不能讀取？還是怎麼樣？

對於動態產生的元素使用on

 $('body').on('click','.category' , function() {         alert(123);     })

在你用一個新 API 之前，應通過文檔充分瞭解它的作用。

