How to properly write this JS script in PHP echo?

To simplify, I will first give you an example with the url saved as a variable.

$url = base_url('assets/inspinia/js/jquery-2.1.1.js');

echo "<script src='$url'></script>";

You can keep it in the long form if you prefer, but you would need to leave the quotes and concatenate (similar to what you have been doing)

echo "<script src='" . base_url('assets/inspinia/js/jquery-2.1.1.js') . "'></script>";

For that reason, I always prefer to assign it to a variable first so that I can see the separation of "get value" and then "print string including that value"

Here is an example of using javascript in php echo:

<?php
echo '<script>Hello World!</script>';
?>

I'm a bit sorry to see what you mean, is that so?

echo "<script  type='text/javascript'>
function getState(){            
        var cs = ".$state.";
        return cs;
} 
</script>";

Do you want to introduce JS files in PHP? You can wrap yourself,and you can refer to YII2's wording, like this：

/**
 * 定义按需加载JS方法
 * @param $view View
 * @param $jsfile
 */
public static

function addScript($view, $jsfile) {
  $AssetManager = new AssetManager();
  $jsfile = $AssetManager - > getPublishedUrl('@backend/modules/motorcade/assets').$jsfile;
  $view - > registerJsFile($jsfile, [motorcadeUIAsset::className(), 'depends' => 'backend\modules\motorcade\assets\motorcadeUIAsset']);
}

Hope it helps you

Try this,

echo "<script src=" '. base_url('assets/inspinia/js/jquery-2.1.1.js') .' "></script>";