{"id":1218,"date":"2022-08-30T15:14:21","date_gmt":"2022-08-30T15:14:21","guid":{"rendered":"https:\/\/unknownerror.org\/index.php\/2013\/11\/10\/jquery-ajax-and-json-how-to-check-if-undefined-collection-of-common-programming-errors\/"},"modified":"2022-08-30T15:14:21","modified_gmt":"2022-08-30T15:14:21","slug":"jquery-ajax-and-json-how-to-check-if-undefined-collection-of-common-programming-errors","status":"publish","type":"post","link":"https:\/\/unknownerror.org\/index.php\/2022\/08\/30\/jquery-ajax-and-json-how-to-check-if-undefined-collection-of-common-programming-errors\/","title":{"rendered":"Jquery Ajax and Json : How to check if undefined-Collection of common programming errors"},"content":{"rendered":"

I got this Jquery code :<\/p>\n

$.ajax({\n    url: \"?module=gestionApplication&action=getTests&scenario=\"+encodeURI(scenario)+\"&application=\"+$application,\n    dataType:'json',\n    success: function( data ) {\n        $.each(data, function(i, item) {\n            $(\"#tests tbody\").append($tr+\"<\/code><\/pre>\n\"+item.ID+\"<\/code><\/td>\n
\" + \"<\/code><\/p>\n\"+ \"Header : \"+item.HEADER + '
\n' + \"M\u00e9thode : \"+item.METHODE + '
\n' + \"PostBody : \"+item.POSTBODY + '
\n' + \"URL : \"+item.URL + '
\n' + \"ParseReponse : \"+item.PARSEREPONSE + '
\n' + \"<\/code><\/td>\n
\" +<\/code><\/p>\n
So i got a JSON response from my server, but not all fields are full. Sometimes item.HEADER or item.METHODE can not be defined, so I get “undefined” text in my table. Problem is, I’m French and I would like different text and not this ‘undefined’.<\/p>\n
So how can I test if the variable is defined or not? Or even better, is it possible to change this ‘undefined’ text to different text in case the variable is not defined?<\/p>\n
    \n
  1. \n
    You can do a quick conditional \/ logical-OR check within your concat:<\/p>\n
    \"Header : \" + (item.HEADER || '') + '
    ' +\n<\/code><\/pre>\n
    so now, if item.HEADER<\/code> is undefined<\/code> we will encounter the empty string instead. Of course you could also use a more expressive string like \"empty\"<\/code> or whatnot.<\/p>\n<\/li>\n
  2. \n
    if (typeof variable == \"undefined\")\n{\n    \/\/ variable is undefined\n}\n<\/code><\/pre>\n<\/li>\n
  3. \n
    Use a ternary operator… ( test ? do if true : do if false )<\/p>\n
    ...+( item.HEADER ? item.HEADER : \"something french\" )+...\n<\/code><\/pre>\n<\/li>\n
  4. \n
    easily done like so:<\/p>\n
    if (item.HEADER === undefined) {\n    item.HEADER = 'ind\u00e9fini';\n}\n\n\/\/ or \n\nif (typeof item.HEADER === 'undefined') {\n    item.HEADER = 'ind\u00e9fini';\n}\n<\/code><\/pre>\n<\/li>\n<\/ol>\n
    Originally posted 2013-11-10 00:10:33. <\/small><\/p>","protected":false},"excerpt":{"rendered":"
    I got this Jquery code : $.ajax({ url: “?module=gestionApplication&action=getTests&scenario=”+encodeURI(scenario)+”&application=”+$application, dataType:’json’, success: function( data ) { $.each(data, function(i, item) { $(“#tests tbody”).append($tr+” “+item.ID+” ” + ” “+ “Header : “+item.HEADER + ‘ ‘ + “M\u00e9thode : “+item.METHODE + ‘ ‘ + “PostBody : “+item.POSTBODY + ‘ ‘ + “URL : “+item.URL + ‘ ‘ + “ParseReponse […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-1218","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts\/1218","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/comments?post=1218"}],"version-history":[{"count":0,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts\/1218\/revisions"}],"wp:attachment":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/media?parent=1218"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/categories?post=1218"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/tags?post=1218"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}