How to skip if substring is null and avoid error in console?

Question

Grab the substring:

var hash = document.location.hash;

// create an object to act like a dictionary to store each value indexed by its key
var partDic = {};

// remove the leading "#" and split into parts
var parts = hash.substring(1).split('&');

// If you just want the first value, whatever it is, use this.
// But be aware it's a URL so can be set to anything in any order, so this makes little sense
// var string = parts[0].split('=')[1];

// build the dictionary from each part
$.each(parts, function(i, v) {
  // do the "=" split now
  var arr = v.split("=");

  // decode to turn "%5B" back into "[" etc
  var key = decodeURIComponent(arr[0]);
  var value = decodeURIComponent(arr[1]);

  // store in our "dictionary" object
  partDic[key] = value;
});

// Set a delay to wait for content to fully load
setTimeout( function() {
  var ag = partDic["comboFilters[Agencies]"].substring(1);
  $('.Agency .dropdown-toggle').html(ag).append(' <span class="caret"></span>');
  var cl = partDic["comboFilters[Clients]"].substring(1);
  $('.Client .dropdown-toggle').html(cl).append(' <span class="caret"></span>');
  var yr = partDic["comboFilters[Years]"].substring(1).slice(1);
  $('.Year .dropdown-toggle').html(yr).append(' <span class="caret"></span>');
}, 1000);

But if there is not a substring, I am getting:

Uncaught TypeError: Cannot read property 'substring' of undefined

Suggested answer in another question

var cl = (partDic["comboFilters[Clients]"] && partDic["comboFilters[Clients]"].length>0)?partDic["comboFilters[Clients]"].substring(1):'';

But I still get the same error

see : http://stackoverflow.com/questions/25973300/can-i-use-the-in-keyword-to-test-a-property-in-an-tree-object — Hacketo, Jan 16 '15 at 10:28

score 6 · Accepted Answer · answered Jan 16 '15 at 10:26

6

You can be defensive and check if a key exists before using it:

  if("comboFilters[Agencies]" in partDic) {
       var ag = partDic["comboFilters[Agencies]"].substring(1);
       $('.Agency .dropdown-toggle').html(ag).append(' <span class="caret"></span>');
  }

or just safeguard it with an empty string:

var ag = (partDic["comboFilters[Agencies]"] || "").substring(1);

answered Jan 16 '15 at 10:26

georg

211,518
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1

Like the second one. – CodeSmith Feb 15 '17 at 21:58

andrusieczko · Answer 2 · 2015-01-16T10:54:11.870

4

Maybe try with things like:

var parts = (hash && hash.substring(1).split('&')) || [];

edited Jan 16 '15 at 10:54

answered Jan 16 '15 at 10:24

andrusieczko

2,824
12
23

score 0 · Answer 3 · answered Jan 16 '15 at 10:23

0

You can try to check it's type:

var cl = (typeof partDic["comboFilters[Clients]"] === 'string')?partDic["comboFilters[Clients]"].substring(1):'';

Note, that you should add this check for all your variables: ag, cl, yr

answered Jan 16 '15 at 10:23

antyrat

27,479
9
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76

that is not creating an error but it is changing the text empty – rob.m Jan 16 '15 at 10:26
Correct, that means that `partDic["comboFilters[Clients]"]` type is not `string`. And `substring` method works only on strings. What does `console.log(partDic["comboFilters[Clients]"])` says? – antyrat Jan 16 '15 at 10:27

score 0 · Answer 4 · answered Jan 16 '15 at 10:25

0

You can check one condition before using substring method..

if((!hash) || (!hash.substring(1)){
return false;
}

answered Jan 16 '15 at 10:25

Paresh Makwana

189
2
14

How to skip if substring is null and avoid error in console?

4 Answers4