How to find the index of matched element in an array

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Posted on by YW-20080832-0

In power automate, I found that there only exists indexOf function for string and no similar function for array.

Is there anyway to extract the index number of an array if element matches?

For example, I have an array variable named varCityArray which holds value like

[
"New York",
"London",
"Paris",
"Tokyo"
]

If I want to search for "Paris", it should return 2.

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stampcoin 5,153 Super User 2026 Season 1 on at

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@YW-20080832-0 Hi,

If you want to use the index value, probably loop each item of the array to get it.

Loop until

variables('myArray')[variables('counter')] ='Paris'

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Chriddle 8,691 Super User 2026 Season 1 on at

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I'm pretty sure there's a better way, but for now:

Compose

The array must not be empty.

Select

From:

range(0, length(outputs('Compose')))

Map:

if( equals('Paris', outputs('Compose')[item()]), item(), -1 )

Compose_2

max(body('Select'))

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Chriddle 8,691 Super User 2026 Season 1 on at

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This also works:

if( contains( outputs('Compose'), 'Paris' ), if( equals( first(outputs('Compose')), 'Paris' ), 0, if( equals( last(outputs('Compose')), 'Paris' ), sub( length(outputs('Compose')), 1 ), length( split( first( split( join(outputs('Compose'), '-|-'), '-|-Paris-|-' ) ), '-|-' ) ) ) ), -1 )

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Chriddle 8,691 Super User 2026 Season 1 on at

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Or this:

if( contains( string(outputs('Compose')), '"Paris"' ), length( json( concat( '[', slice( string(outputs('Compose')), 1, sub( indexOf( string(outputs('Compose')), '"Paris"' ), 1 ) ), ']' ) ) ), -1 )

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Chriddle 8,691 Super User 2026 Season 1 on at

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Or this:

if( contains( outputs('Compose'), 'Paris' ), sub( length( xpath( xml( addProperty( json('{}'), 'Root', addProperty( json('{}'), 'Item', outputs('Compose') ) ) ), '//Item[not(preceding::*/text()="Paris")]' ) ), 1 ), -1 )

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Chriddle 8,691 Super User 2026 Season 1 on at

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And finally (what I like best):

xpath( xml( addProperty( json('{}'), 'Root', addProperty( json('{}'), 'Item', outputs('Compose') ) ) ), 'count(//Item[following::*/text()="Paris" or ./text()="Paris"]) - 1' )

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