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[Pro-Tip] Angular Input syntax

pietrucha profile image Bartosz Pietrucha twitter logo ・1 min read

It's time for another Angular Knowledge Pill! πŸ’Š It takes just 10 seconds to learn something new πŸ”₯ Like taking your morning vitamins πŸ˜ƒ

When you use [input]="value" then Angular interprets the value as an expression. So you can place there a variable reference from the component or even mathematic formula. When you use input="value" then the value is interpreted as a string! Take a look at the example:

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Important to note as the conventional understanding is that bracketed syntax represents a binding and non-bracketed a static value. As such you might expect foo="false" to be false, but in fact, since it's a string, TypeScript/JavaScript will interpret it as truthy. Counter-intuitively, static value booleans require the square bracket 'binding' syntax.


Great tip!. This actually happened to me long time ago, I was trying to pass a string instead of a component's property; Took me almost 30min to figure that out hehe, I guess I learned the hard way. Cheers. Thanks for sharing.

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