[Smarty] initializing JavaScript variables with smarty variables in the smarty template

//Summary:
1/In the Smarty template file, using the Smarty variable assign from PHP, you must use double or single quotes to enclose the smarty variable, such as: Var title= "<!--{$title}-->";
2/If it is not enclosed in quotation marks, if the value of the Smarty variable is a string, then the string is interpreted as a JavaScript variable in JavaScript, resulting in an error.
3/Variable value is a number, then no error is generated
//TPL file<script>if(Navigator.userAgent.toLowerCase (). Match (/app_.*_hinabian/)){            <!--{ifIsset ($APP _page_title)}-->Document.title= <!--{$APP _page_title|default: ' All immigration programs '}-->; //There is no quotation mark (single or double quotes) around the smarty variable value, if the Smarty variable is a string, then in JavaScript will be treated as a variable, so there will be uncaught Referenceerror <!--{Else}-->Document.title= Document.title.replace (' Sea side ', '). Replace (' sea side ', '). Replace (' _ Sea side ', ' '); <!--{/if}-->        }</script>//data returned to the browser after PHP + smarty processing<script>if(Navigator.userAgent.toLowerCase (). Match (/app_.*_hinabian/) ) {Document.title=General immigrant Investor Program;}</script>

Error message:

[Smarty] initializing JavaScript variables with smarty variables in the smarty template