Angular 2 ngfor first last index loop

Question

I m trying to set as default the first occurrence in this example  plunkr getting the following error      Unhandled Promise rejection  Template parse errors      TypeError  Cannot read property  toUpperCase  of undefined   quot dButtonToggleGroup quot  gt       lt md-button-toggle  ERROR - gt   ngFor  quot let indicador of indicadores   first   first quot  value  quot indicador id quot   checked   quot first quot  gt  quot    ng    AppModule HomeComponent html 35 78     Parser Error  Unexpected token    expected identifier  keyword  or string at column 31 in  let indicador of indicadores   first   first  in ng    AppModule HomeComponent html 35 78   quot  lt md-button-toggle  ngFor  quot let indicador of indicadores   first   first quot  value  quot indicador id quot   ERROR - gt   checked   quot first quot  gt       lt span gt    indicado quot    ng    AppModule HomeComponent html 35 153  what is wrong

User · Answer

By this you can get any index in  ngFor loop in ANGULAR      lt ul gt     lt li  ngFor  quot let object of myArray  let i   index  let first   first  let last   last  quot  gt       lt div  ngIf  quot first quot  gt            write your code         lt  div gt        lt div  ngIf  quot last quot  gt            write your code         lt  div gt     lt  li gt   lt  ul gt   We can use these alias in  ngFor  index   number   let i   index to get all index of object  first   boolean   let first   first to get first index of object  last   boolean   let last   last to get last index of object  odd   boolean   let odd   odd to get odd index of object  even   boolean   let even   even to get even index of object

User · Answer

Here is how its done in Angular 6   lt li  ngFor  let user of userObservable   first as isFirst  gt      lt span  ngIf  isFirst  gt default lt  span gt   lt  li gt    Note the change from let first   first to first as isFirst

User · Answer

Check out this plunkr   When you re binding to variables  you need to use the brackets  Also  you use the hashtag when you want to get references to elements in your html  not for declaring variables inside of templates like that    lt md-button-toggle  ngFor  let indicador of indicadores  let first   first    value   indicador id   checked   first  gt           Edit  Thanks to Christopher Moore  Angular exposes the following local variables    index first last even  odd

[angular] Angular 2 ngfor first, last, index loop

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