java - javascript error when accesssing flash redirect attribute (thymeleaf, springmvc) -

i'm stuck following problem springmvc, thymeleaf , javascript.

1) server-side: under circumstances add flash redirect attribute in controller before redirecting page.

redirectattributes.addflashattribute("mycondition", true); 

2) client-side: in case attribute exists, want javascript function execute additional code.

window.onload = function() {     ...     if([[${mycondition}]]) {         //do     } } 

this works fine after redirect, on first enter redirect attribute not exist, results in following javascript code being rendered:

    window.onload = function() {     if() {         //do     } } 

this code not valid , therefore produces javascript error. i'm not sure how check javascript if redirect attribute exists? has run similar problem before?

can try following code , let me know if works declare variable mycondition

var mycondition = [[${mycondition}]];  if(mycondition) {    //do } 

hope helps