javascript - Data of type undefined has no value? -

-

in javascript, type "undefined" supposed have 1 value "undefined". however, in example below, undeclared xxx has type "undefined" apparently has no value of kind. not make difference js throws exception because of no value in xxx. consistent js should throw exception on typeof xxx. otherwise, have big hole in logic here. 

<!doctype html> <html> <body>  <script> document.write("type=" + typeof xxx); document.write(", value="); document.write(xxx); </script>  </body> </html>

you need first at:

in example never declare xxx variable, therefore when document.write(xxx) variable xxx doesn't exist.

var xxx; document.write("type=" + typeof xxx); document.write(", value="); document.write(xxx);

declaring var xxx; no value instantiate , since has no value assigned, default assignment undefined stated in data types.


Comments

Post a Comment

Popular posts from this blog

javascript - Hide toolbar of pdf file opened inside iframe using firefox -

-
other browsers such chrome,ie working fine when given #toolbar=0.but not working in firefox. please help. this code. <html> <body> <iframe src="reports/reports.pdf#toolbar=0" width="100%;" height="80%"> </iframe> </html> i think it's dependent on application/plugin in browser opens pdf, works differently , might ignore there directives (depending on browser, plugin, platform, pdf viewer). the general recommendation here use these "directives" @ end of url: #toolbar=0&navpanes=0 you may try recommendations http://blogs.adobe.com/pdfdevjunkie/web_designers_guide : embedding using pdfobject you use basic html markup embed pdf files in page there more elegant solution out there. take @ pdfobject philip hutchison. pdfobject pretty easy scripting tool dynamically embedding pdf files web pages. uses javascript inject element dom tree of html file. there’s...
Read more

Ansible - ERROR! the field 'hosts' is required but was not set -

-
i've error when launch playbook don't found why.... error! field 'hosts' required not set there main.yml : --- - hosts: hosts - vars: - elasticsearch_java_home: /usr/lib/jmv/jre-1.7.0 - elasticsearch_http_port: 8443 - tasks: - include: tasks/main.yml - handlers: - include: handlers/main.yml and /etc/ansible/hosts : [hosts] 10.23.108.182 10.23.108.183 10.23.108.184 10.23.108.185 when test ping, : [root@poste08-08-00 elasticsearch]# ansible hosts -m ping 10.23.108.183 | success => { "changed": false, "ping": "pong" } 10.23.108.182 | success => { "changed": false, "ping": "pong" } 10.23.108.185 | success => { "changed": false, "ping": "pong" } 10.23.108.184 | success => { "changed": false, "ping": "pong" } please, me :) regards, you have syntax error in playbook. ...
Read more

Copy range with conditional formatting -

-
i have range conditional formatting in existing excel file. used epplus copy range new sheet, found conditional formatting missing. is there way copy range conditional formatting using epplus? i found solution this. did not test on formattingruletypes. (only needed 2 of them moment) in application have 1 template row each sheet. var formatlist = fromsheet.conditionalformatting.tolist(); foreach (var cf in formatlist) { // sourcerow row containing formatting if (cf.address.start.row == sourcerow ) { iexcelconditionalformattingrule rule = null; switch (cf.type) { case officeopenxml.conditionalformatting.eexcelconditionalformattingruletype.greaterthan: rule = dest.conditionalformatting.addgreaterthan(); break; case officeopenxml.c...
Read more