Error: Unable to get property 'lastIndexOf' of undefined or null reference

Posted on 2014-02-25
Last Modified: 2014-02-25
i'm getting this error on IE10 browser for but this is happening only in one instant..
MasterScriptIns = MasterScriptIns.nextSibling;
    var InnerScript = MasterScriptIns.innerHTML;
    var Index = InnerScript.lastIndexOf("WebForm_AutoFocus('");
    if(Index == -1)
        return false;

please advice
Question by:Saikat M
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LVL 44

Accepted Solution

AndyAinscow earned 500 total points
ID: 39885470
Does this work?  

var InnerScript = MasterScriptIns.innerHTML;
if(InnerScript != null)
    var Index = InnerScript.lastIndexOf("WebForm_AutoFocus('");
    if(Index == -1)
        return false;
LVL 22

Expert Comment

by:Ivo Stoykov
ID: 39885482

This means that MasterScriptIns.innerHTML returns something different than string.

You have to make a check after each assignment to see what have you gotten.

you could restate this as follow:
MasterScriptIns = MasterScriptIns.nextSibling; // you have to check after this assignment.
var InnerScript = MasterScriptIns.innerHTML || ""; // in the case InnerScript will be empty string and won;t fire the error

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Ivo Stoykov

Author Comment

by:Saikat M
ID: 39885502
Thanks a ton. It worked out.
LVL 44

Expert Comment

ID: 39885545
A rapid response, A correct answer (with code) that works. Then why only a 'B' grade?

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