可以通过过滤的输出来删除宽度和高度属性image_downsize 函数位于wp-includes/media.php. 要做到这一点，您需要编写自己的函数，并通过主题函数执行它。php文件或作为插件。

Example:

/**
 * This is a modification of image_downsize() function in wp-includes/media.php
 * we will remove all the width and height references, therefore the img tag 
 * will not add width and height attributes to the image sent to the editor.
 * 
 * @param bool false No height and width references.
 * @param int $id Attachment ID for image.
 * @param array|string $size Optional, default is \'medium\'. Size of image, either array or string.
 * @return bool|array False on failure, array on success.
 */
function myprefix_image_downsize( $value = false, $id, $size ) {
    if ( !wp_attachment_is_image($id) )
        return false;

    $img_url = wp_get_attachment_url($id);
    $is_intermediate = false;
    $img_url_basename = wp_basename($img_url);

    // try for a new style intermediate size
    if ( $intermediate = image_get_intermediate_size($id, $size) ) {
        $img_url = str_replace($img_url_basename, $intermediate[\'file\'], $img_url);
        $is_intermediate = true;
    }
    elseif ( $size == \'thumbnail\' ) {
        // Fall back to the old thumbnail
        if ( ($thumb_file = wp_get_attachment_thumb_file($id)) && $info = getimagesize($thumb_file) ) {
            $img_url = str_replace($img_url_basename, wp_basename($thumb_file), $img_url);
            $is_intermediate = true;
        }
    }

    // We have the actual image size, but might need to further constrain it if content_width is narrower
    if ( $img_url) {
        return array( $img_url, 0, 0, $is_intermediate );
    }
    return false;
}

/* Remove the height and width refernces from the image_downsize function.
 * We have added a new param, so the priority is 1, as always, and the new 
 * params are 3.
 */
add_filter( \'image_downsize\', \'myprefix_image_downsize\', 1, 3 );

/* Image sizes and alignments */
.entry-content img,
.comment-content img,
.widget img {
    max-width: 97.5%; /* Fluid images for posts, comments, and widgets */
}
img[class*="align"],
img[class*="wp-image-"] {
    height: auto; /* Make sure images with WordPress-added height and width attributes are scaled correctly */
}
img.size-full {
    max-width: 97.5%;
    width: auto; /* Prevent stretching of full-size images with height and width attributes in IE8 */
}

干杯

您可以使用post_thumbnail_html 筛选以删除属性：

function remove_img_attr ($html) {
    return preg_replace(\'/(width|height)="\\d+"\\s/\', "", $html);
}

add_filter( \'post_thumbnail_html\', \'remove_img_attr\' );

您可以使用!important:

.wp-post-image {
    width: auto !important; /* or probably 100% in case of a grid */
    height: auto !important; 
}

Best solution is to place jquery in footer

jQuery(document).ready(function ($) {
    jQuery(\'img\').removeAttr(\'width\').removeAttr(\'height\');
});

CSS solution:

img[class*="align"], img[class*="wp-image-"] {
    width: auto;
    height: auto;
}

PHP solution:

function remove_widthHeight_attribute( $html ) {
   $html = preg_replace( \'/(width|height)="\\d*"\\s/\', "", $html );
   return $html;
}

add_filter( \'post_thumbnail_html\', \'remove_widthHeight_attribute\', 10 );
add_filter( \'image_send_to_editor\', \'remove_widthHeight_attribute\', 10 );

下面是一个简单的Javascript解决方案：

<script type="text/javascript">
jQuery.noConflict();
jQuery(document).ready(function($){
  $(\'img\').each(function(){
  $(this).removeAttr(\'width\')
  $(this).removeAttr(\'height\');
 });
});
</script>

 $(\'.myspecificclass img\').each(function()

添加以下代码：（也适用于新的Gutenberg编辑器）

function disable_add_img_width_height( $value, $image, $context, $attachment_id ) {
    if ($context === \'the_content\' || $context === \'the_excerpt\' ||  $context === \'widget_text_content\')
        return false;
    return $value;
}
add_filter( \'wp_img_tag_add_width_and_height_attr\', \'disable_add_img_width_height\', 10, 4 );