Input pattern is parsed wrong in template file. escape character is omitted

Questions
1 
<div class="item-input-wrap">
    <input name="gsm" type="text" pattern="[+\s()0-9]{10,}" required validate data-error-message="Telefon numaranızı başında 0 olmadan 10 hale şeklinde giriniz!" placeholder="5325323232" />
    <span class="input-clear-button"></span>
</div>

here i have an input with a pattern which ckecks lightly gsm number format. However, once the tempalte is rendered, the patterns is show as below:

<div class="item-input-wrap">
    <input name="gsm" type="text" pattern="[+s()0-9]{10,}" validate="" data-error-message="Telefon numaranızı başında 0 olmadan 10 hale şeklinde giriniz!" placeholder="5325323232" required="">
    <span class="input-clear-button"></span>
</div>

This causes the error:
Pattern attribute value [+s()0-9]{10,} is not a valid regular expression: Uncaught SyntaxError: Invalid regular expression: /[+s()0-9]{10,}/v: Invalid character in character class.

2

Try using a double backslash (\\) in the template, to render a single backslash.