how to check for special characters in javascript

var format = /[ `!@#$%^&*()_+\-=\[\]{};':"\\|,.<>\/?~]/;
//            ^                                       ^   
document.write(format.test("My@string-with(some%text)") + "<br/>");    //true
document.write(format.test("My string with spaces") + "<br/>");        //true 
document.write(format.test("MyStringContainingNoSpecialChars"));       //false