.js codes inside a PHP

[smartcard]

How can I put the following .js codes inside a PHP code (I mean I don't want to attaché a .js file with my codes, instead I need to embed the codes inside a PHP file)

}
function Big_Photo(target, filename) {
document[target].src = "/photo/" + Big_filename;
}

[Span]

echo ("function Big_Photo(target, filename) {
document[target].src = \"/photo/\" + Big_filename;
}");