Question

$('select[name^="salesrep"] option[value="Bruce Jones"]').attr("selected","selected");

如何在javascript中编写上面的代码？

Answer 1

您可以使用querySelector，如下所示

＆＃13;

public class MyPermission {

private static final int PERMISSION_REQUEST_ALL = 127;
private MainActivity mMainActivity;

MyPermission(MainActivity mainActivity) {
    mMainActivity = mainActivity;
}

public static boolean hasPermission(String permission, Context context) {
    if (isNewPermissionModel()) {
        return (ActivityCompat.checkSelfPermission(context, permission) == PackageManager.PERMISSION_GRANTED);
    }
    return true;
}

private static boolean hasPermissions(Context context, String... permissions) {
    if (isNewPermissionModel() && context != null && permissions != null) {
        for (String permission : permissions) {
            if (ActivityCompat.checkSelfPermission(context, permission) != PackageManager.PERMISSION_GRANTED) {
                return false;
            }
        }
    }
    return true;
}

private static boolean shouldShowRationale(Activity activity, String permission) {
    return isNewPermissionModel() && ActivityCompat.shouldShowRequestPermissionRationale(activity, permission);
}

private static boolean isNewPermissionModel() {
    return VERSION.SDK_INT > VERSION_CODES.LOLLIPOP_MR1;
}


/**
 * check all permissions
 */
void checkAll() {
    //check dangerous permissions, make request if need (Android will ask only for the ones it needs)
    String[] PERMISSIONS = {
            permission.READ_CALENDAR,           
            permission.ACCESS_COARSE_LOCATION   
    };

    if (!hasPermissions(mMainActivity, PERMISSIONS)) {
        ActivityCompat.requestPermissions(mMainActivity, PERMISSIONS, PERMISSION_REQUEST_ALL);
    }
}

void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    if (requestCode == PERMISSION_REQUEST_ALL) {
        if (grantResults.length > 0) {
            //for not granted
            for (int i = 0; i < permissions.length; i++) {

                if (permissions[i].equals(permission.READ_CALENDAR)) {
                    if (grantResults[i] != PackageManager.PERMISSION_GRANTED) {
                        smartRequestPermissions(permission.READ_CALENDAR, R.string.permission_required_dialog_read_calendar);
                    }
                } else if (permissions[i].equals(permission.ACCESS_COARSE_LOCATION)) {
                    if (grantResults[i] != PackageManager.PERMISSION_GRANTED) {
                        smartRequestPermissions(permission.ACCESS_COARSE_LOCATION, R.string.permission_required_dialog_access_coarse_location);
                    }
                }

            }
        }
    }
}

private void smartRequestPermissions(final String permissionName, int permissionRequiredDialog) {
    if (shouldShowRationale(mMainActivity, permissionName)) {// If the user turned down the permission request in the past and chose the Don't ask again option in the permission request system dialog, this method returns false.

        //Show an explanation to the user with action
        mMainActivity.mSnackProgressBarManager.show(
                new SnackProgressBar(
                        SnackProgressBar.TYPE_ACTION, mMainActivity.getString(permissionRequiredDialog)
                )
                        .setAction("OK", new OnActionClickListener() {
                            @Override
                            public void onActionClick() {
                                checkAll();
                            }
                        })
                        .setSwipeToDismiss(true).setAllowUserInput(true)
                , MainActivity.SNACKBAR_WARNING_DURATION
        );

    } // else do nothing
}

＆＃13;

document.querySelector('select[name^="salesrep"] option[value="Bruce Jones"]').selected = true;

＆＃13;

Answer 2

JavaScript的：

var mySelect = document.getElementById('salesrep');
for(var i, j = 0; i = mySelect.options[j]; j++) {
    if(i.value == 'Bruce Jones') {
        mySelect.selectedIndex = j;
        break;
    }
}

<select name="salesrep" id="salesrep">
<option value="Bruce Jones">Bruce Jones</option>
<option value="John Doo">John Doo</option>
<option value="John Lee">John Lee</option>
<option value="Jane Doo">Jane Doo</option>
</select>

使用Javascript在下拉列表中选择一个值

2 个答案: