我如何在 PHP 和 Javascript 的代码中使用 ' 和 "？

Question

I'd like how i can use a lot of ' and " in a code.

Example:

echo 'document.write("<a href='$url'> <img src='{$row["image"]}' border='0' /> </a>");';

I tried but i'm getting error. Anyone can help?

Answer 1

so, you have multi-level problem here:

1. data which is echoed to html, usually should be properly escaped via htmlspecialchars
2. you want to see document.write("..."..."); in your finally produced html, this will trigger javascript syntax error
3. to avoid this error, you should use \\ before " inside string

echo 'document.write("<a href=\\"' . htmlspecialchars($url) . '\\"><img src=\\"' . htmlspecialchars($row["image"]) . '\\" border=\\"0\\" /></a>");';

note: I'm using echo with single quotes, if you're using double quotes - you will have to double \\\\

in case of double quotes your code will look like:

echo "document.write(\\"<a href=\\\\\\"" . htmlspecialchars($url) . "\\\\\\"><img src=\\\\\\"" . htmlspecialchars($row["image"]) . "\\\\\\" border=\\\\\\"0\\\\\\" /></a>\\");";

Answer 2

Here are three ways to tackle this problem.

1. Escaping the inner double slashes

echo "document.write('<a href=\\"$url\\"> <img src=\\"{$row['image']}\\" border=\\"0\\" /> </a>');";

2. Closing your PHP tags and writing javascript

?> document.write('<a href="<?php echo $url; ?>"> <img src="<?php echo $row['image']; ?>" border="0" /> </a>'); <?php

3. Using Heredoc syntax

echo <<<EOJS document.write('<a href="$url"> <img src="{$row['image']}" border="0" /> </a>'); EOJS;

Answer 3

This will work:

<?php
$url = "http://www.google.com";
$row = array("image" => "image.png");
echo "document.write('<a href=\"$url\"> <img src=\"".$row["image"]."\" border=0 /> </a>');";
// output: document.write('<a href="http://www.google.com"> <img src="image.png" border=0 /> </a>');
?>

Answer 4

You can use the heredoc syntax:

echo <<<EOT
document.write(<a href='{$url}'> <img src='{$row["image"]}' border='0' /> </a>);

EOT;

From phpdocs

Heredoc text behaves just like a double-quoted string, without the double quotes. This means that quotes in a heredoc do not need to be escaped, but the escape codes listed above can still be used. Variables are expanded, but the same care must be taken when expressing complex variables inside a heredoc as with strings.

Also note, that

It is very important to note that the line with the closing identifier must contain no other characters, except a semicolon (;). That means especially that the identifier may not be indented, and there may not be any spaces or tabs before or after the semicolon. It's also important to realize that the first character before the closing identifier must be a newline as defined by the local operating system. This is \\n on UNIX systems, including Mac OS X. The closing delimiter must also be followed by a newline.