问题
I'm working with a Reactive form and I have noticed in some tutorials they do the following:
HTML
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<input type="text" formControlName="firstName" required>
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.
TS
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firstName: ['', Validators.required]
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.
QUESTION:
Why do I need to specify "required" in the HTML if I just do it in the TS file it works fine?
回答1:
Actually, Angular mention something about that here:
Caution: Use these HTML5 validation attributes in combination with the built-in validators provided by Angular's reactive forms. Using these in combination prevents errors when the expression is changed after the template has been checked.
来源：https://stackoverflow.com/questions/53583529/angular-reactive-form-validation