Angular's expression is incapable of determining the variable's type through the use of the constructor property


I attempted to use an angular expression to determine if a scope variable is an array. However, when using variable.constructor === Array for the check, the result always showed as false.

It was only when I used a scope function with 

return variable.constructor === Array
that I received the correct result.

Could someone explain why the expression behaves this way? Also, is there a way to perform the same check as an inline expression statement?

You can see a Plunker showcasing the issue here
Thank you.

javascriptangularjs

Answer №1

The absence of the variable named Array within your current scope means that the evaluation of variable.constructor === Array essentially equates to 

variable.constructor === undefined
.

This is the reason why the result will consistently be false.

Answer №2

In this scenario, you're comparing a value to undefined because Array is not recognized.

If you want to validate if a value is an array, Angular provides a built-in function called isArray().

For further details, refer to the following answer: Angular expression to check if model is array or object

Answer №3

To check if a variable is an array in JavaScript, you can use the Array.isArray(variable) method.

For more information, visit this link: on MDN

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