<html> <head> </head> <body> <textarea id=txt></textarea> <button id="check_txt">check_txt</button> <button id="check_var">check_var</button> <button id="reset">reset</button> <script> myvar=0 check_txt.onclick=function(){ if(/\d/.test(txt.value)) myvar=1 } check_var.onclick=function(){alert(myvar)} reset.onclick=function(){myvar=0} </script> </body> </html>
myvar = +/\d/.test(txt.value);
myvar = Number(/\d/.test(txt.value));