Some useful functions for sanitization, validation, and escaping output

security_io.php

<?php

function mm_sanitize($unsanitized_input) {
  //calls a WordPress core function
  //verifies UTF-8 encoding, strips tags
  //removes whitespace/newlines & octets
  //reference: 
  //https://codex.wordpress.org/Function_Reference/sanitize_text_field
  return sanitize_text_field($unsanitized_input);
}

function mm_float_validate($unvalidated_input) {
  //Returns the numerical float value of the input
  //junk strings and arrays return 0.0
  //reference: http://php.net/manual/en/function.floatval.php
  return floatval($unvalidated_input);
}

function mm_esc_js($js_val) {
  //escapes the newline & other unexpected tokens
  //prior to outputting them on the page
  //JSON_NUMERIC_CHECK option converts strings to
  //their numeric equivalents
  //reference: http://php.net/manual/en/function.json-encode.php
  return json_encode($js_val, JSON_NUMERIC_CHECK);
}

?>