Parser Error: Got interpolation ({{}}) where expression was expected

Question

I'm using ng-bootstrap as a substitute for ui-bootstrap in angular2.

My html is as follows:

<ul class="list-inline">
    <li class="tag" ngb-dropdown auto-close="outsideClick" 
        *ngFor="let item of ['Elastic Search','Database Theory','CVS'];
        let $index=index;" 
        [ngClass]="{'default-tag': $index==0, 'matched-tag': $index==1, 'unmatched-tag': $index==2 }">
         <a href ngb-dropdown-toggle id="desiredSkill{{$index}}">
             <i class="bi_interface-tick following"></i> {{item}} <i class="bi_interface-more tag-menu-icon"></i>
                            </a>
               <ul class="dropdown-menu tag-menu" ngb-dropdown-menu [aria-labelledby]="desiredSkill{{$index}}">
                     <li><a href>Follow Skill</a></li>
                     <li><a href>Related Jobs</a></li>
                </ul>
     </li>
  </ul>

But when I run my app I get following error:

main.browser.ts:25Error: Template parse errors: Parser Error: Got interpolation ({{}}) where expression was expected at column 12 in [desiredSkill{{$index}}] in JobDescription@174:77 (" ][aria-labelledby]="desiredSkill{{$index}}">

"): JobDescription@174:77 Parser Error: Unexpected token '{' at column 13 in [desiredSkill{{$index}}] in JobDescription@174:77 ("
][aria-labelledby]="desiredSkill{{$index}}">

"): JobDescription@174:77 Can't bind to 'aria-labelledby' since it isn't a known property of 'ul'. (" ][aria-labelledby]="desiredSkill{{$index}}">

"): JobDescription@174:77 Parser Error: Got interpolation ({{}}) where expression was expected at column 12 in [desiredSkill{{$index}}] in JobDescription@174:77 ("

                <div class="row">
                  <div class="col-lg-4 col-xs-4" [ERROR ->]*ngFor="let i of [0,1,3]">
                    <img src="http://ecx.images-amazon.com/images/I/81VFU9"):

JobDescription@215:49 Parser Error: Unexpected token '{' at column 13 in [desiredSkill{{$index}}] in JobDescription@174:77 ("

                <div class="row">
                  <div class="col-lg-4 col-xs-4" [ERROR ->]*ngFor="let i of [0,1,3]">
                    <img src="http://ecx.images-amazon.com/images/I/81VFU9"):

JobDescription@215:49 Parser Error: Got interpolation ({{}}) where expression was expected at column 12 in [desiredSkill{{$index}}] in JobDescription@174:77 (" ERROR ->="main.applyJob()">Apply for job ERROR ->="main.applyJob()">Apply for job ][hidden]="!ifNotApplied">Applied ][hidden]="!ifNotApplied">Applied ][hidden]="!ifNotUploaded">Upload CV ][hidden]="!ifNotUploaded">Upload CV Have questions about this job?

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Answer 1

You can't use interpolation inside standard property binding. There should be an expression.

Seems it should be:

[attr.aria-labelledby]="'desiredSkill' + $index"

or

attr.aria-labelledby="desiredSkill{{$index}}"