<?php
 
function minify($html) {
    $lines = explode(PHP_EOL, $html);
    array_walk($lines,
function(&$line) {
        $line = trim($line);
    });
 
    $lines = array_filter($lines, function($line) {
        return $line !== '';
    });
 
    return implode(PHP_EOL, $lines);
}
 
$html = '<div class="container">
 
    <div class="row">
 
        <div class="col-sm-12">
            //content here
        </div>
 
    </div>
 
</div>';
 
$minify = minify($html);
echo ($minify);

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