how to use onblure javscript in php form?

how to use onblure javscript in php form?

I have a php form that i want the value of the form be inside the input
tag and when the input be clicked . the value become disappear i use this
code but i get syntax error.
'<span class="wpcf7-form-control-wrap %1$s"><input value="%1$s"
name="%1$s" onblur="if(this.value == '') {
this.value='Email'}"/>%3$s</span>'
but whe i use this code in html file it work perfectly
<input type="email" value="Email" required=""
name="email" id="cemail" onblur="if(this.value ==
'') { this.value='Email'}" onfocus="if (this.value
== 'Email') {this.value=''}">
if someone help me it will be so appreciated.
thank you.