How do I sanitize the str_replace function in javascript variables

Question

I have the following code in the javascript which outputs the date(s). With backslash for that, I'm replacing those strings with the str_replace to remove backslash, but I can't sanitize that using any escaping function like esc_js.

Stored Days Array

array (size=2)
  0 => string '4/7/2018' (length=8)
  1 => string '11/18/2017'(length=10)

The code

var disabledDays = <?php echo str_replace( '\\/', '/', wp_json_encode( $iva_disable_days ) ); ?>;

Tried Code which is not working

var disabledDays = <?php echo esc_js( str_replace( '\\/', '/', wp_json_encode( $iva_disable_days ) ) ); ?>;

Result Output

var disabledDays = ["4/7/2018","11/18/2017"];

How do I sanitize the above section in The Code

Answer 1

esc_js() is intended for escaping data for use within an HTML attribute.

If you want to escape data for use within an inline script, wp_json_encode() should be sufficient.

For example:

var disabledDays = <?php echo wp_json_encode( $iva_disable_days ); ?>;

This outputs:

var disabledDays = ["4\/7\/2018","11\/18\/2017"];

If you check the variable in your dev tools console, you will see that it is being parsed correctly:

However - if you absolutely do not want escaped slashes (not recommended), the second param to wp_json_encode() is a bitmask of options:

var disabledDays = <?php echo wp_json_encode( $iva_disable_days, JSON_UNESCAPED_SLASHES ); ?>;

This outputs:

var disabledDays = ["4/7/2018","11/18/2017"];

For a list of available options, check the PHP json_encode() docs.