Angular 2 - Check if property is an array

Question

In Angular 2 how do I check if a property is an array?

I have tried constructor but get a function as below:

function Array() { [native code] }

My Code:

let content: any = {id: '1324234', value:{id:null}};
if(content.value.constructor === 'Array'){
 console.log('It is an array');
} else {
 console.log('Not an array');
}

I guess there is nothing to do with angular2 – yurzui Dec 19 '16 at 09:01 — yurzui, Dec 19 '16 at 09:01
well Angular 2 does not have javascript function .isArray() – Ka Tech Dec 19 '16 at 09:24 — Ka Tech, Dec 19 '16 at 09:24

score 39 · Accepted Answer · edited May 23 '17 at 11:54

39

if(content.value instanceof Array){

See also Test for array of string type in TypeScript

edited May 23 '17 at 11:54

Community

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answered Dec 19 '16 at 09:01

Günter Zöchbauer

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Thanks for the prompt response! Works. – Ka Tech Dec 19 '16 at 09:08
Could you please tell how to check this in a template? – Vikram Singh Jan 18 '19 at 04:57
@VikramSingh You can't. You can put this code into a function and call the function from the template (which is usually a bad idea because of performance issues of calling functions from templates). Rather store the result in a variable and bind to this variable from the template. – Günter Zöchbauer Jan 18 '19 at 06:10
but i have dynamic object and i have to display key value pairs in html only if the value is not an Array. I am going with method approach. If you have any better idea please tell me. – Vikram Singh Jan 18 '19 at 07:13
Prepare a data structure that contains the data *and* the result of the type test and use this data structure in the template. – Günter Zöchbauer Jan 18 '19 at 07:18

Angular 2 - Check if property is an array

1 Answers1