Mixing
Angular: regular expression logic
I'm developing a web application using Angular 6. I have a question:
I'm creating a custom input component (for text input) such as:
@Component({
selector: 'input-text',
templateUrl: './input-text.component.html'
]
})
export class InputTextComponent {
@Input() pattern?: string;
}
I would like a user can insert a regular expression for the validation of the input field, in this way:
<input-text pattern="^[a-z0-9_-]{8,15}$"></input-text>
The template of my component is defined like this:
<input type="text" [attr.pattern]="pattern"/>
Unfortunately I know absolutely nothing about regular expressions.
I would like to do two things:
1 - Create a method that checks the validity of the regular expression and changes the visual style.
2 - Make sure that if the input (with a pattern field) is inserted into a form, the attribute form.valid remains false until the expression is valid.
Thanks for your help!
regex angular typescript components
asked Nov 20 '18 at 15:29
claudiozclaudioz
145212
add a comment |
I'm developing a web application using Angular 6. I have a question:
I'm creating a custom input component (for text input) such as:
@Component({
selector: 'input-text',
templateUrl: './input-text.component.html'
]
})
export class InputTextComponent {
@Input() pattern?: string;
}
I would like a user can insert a regular expression for the validation of the input field, in this way:
<input-text pattern="^[a-z0-9_-]{8,15}$"></input-text>
The template of my component is defined like this:
<input type="text" [attr.pattern]="pattern"/>
Unfortunately I know absolutely nothing about regular expressions.
I would like to do two things:
1 - Create a method that checks the validity of the regular expression and changes the visual style.
2 - Make sure that if the input (with a pattern field) is inserted into a form, the attribute form.valid remains false until the expression is valid.
Thanks for your help!
regex angular typescript components
asked Nov 20 '18 at 15:29
claudiozclaudioz
145212
add a comment |
I'm developing a web application using Angular 6. I have a question:
I'm creating a custom input component (for text input) such as:
@Component({
selector: 'input-text',
templateUrl: './input-text.component.html'
]
})
export class InputTextComponent {
@Input() pattern?: string;
}
I would like a user can insert a regular expression for the validation of the input field, in this way:
<input-text pattern="^[a-z0-9_-]{8,15}$"></input-text>
The template of my component is defined like this:
<input type="text" [attr.pattern]="pattern"/>
Unfortunately I know absolutely nothing about regular expressions.
I would like to do two things:
1 - Create a method that checks the validity of the regular expression and changes the visual style.
2 - Make sure that if the input (with a pattern field) is inserted into a form, the attribute form.valid remains false until the expression is valid.
Thanks for your help!
regex angular typescript components
asked Nov 20 '18 at 15:29
claudiozclaudioz
145212
I'm developing a web application using Angular 6. I have a question:
I'm creating a custom input component (for text input) such as:
@Component({
selector: 'input-text',
templateUrl: './input-text.component.html'
]
})
export class InputTextComponent {
@Input() pattern?: string;
}
I would like a user can insert a regular expression for the validation of the input field, in this way:
<input-text pattern="^[a-z0-9_-]{8,15}$"></input-text>
The template of my component is defined like this:
<input type="text" [attr.pattern]="pattern"/>
Unfortunately I know absolutely nothing about regular expressions.
I would like to do two things:
1 - Create a method that checks the validity of the regular expression and changes the visual style.
2 - Make sure that if the input (with a pattern field) is inserted into a form, the attribute form.valid remains false until the expression is valid.
Thanks for your help!
regex angular typescript components
regex angular typescript components
asked Nov 20 '18 at 15:29
claudiozclaudioz
145212
asked Nov 20 '18 at 15:29
claudiozclaudioz
145212
asked Nov 20 '18 at 15:29
claudiozclaudioz
145212
asked Nov 20 '18 at 15:29
claudiozclaudioz
145212
asked Nov 20 '18 at 15:29
claudiozclaudioz
145212
145212
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
- Check regex validity
You can simply catch exceptions thrown by the RegExp constructor when instanciating it.
try {
const regex = new RegExp(pattern);
} catch (error) {
// If it goes here, then the regex model is not correct
console.error(error.message)
}
- Change the visual style
You can simply use the ngClass attribute to change your input style.
If you enter the catch statement, set a style variable to change the class like so
private hasBadInput: boolean;
// [...]
catch (error) {
hasBadInput= true;
}
Then apply a specific class in that case:
<input-text [ngClass]="{'yourErrorClass': hasBadInput}"><input-text>
- Form validity
You did well using [attr.pattern], the form should automatically consider the entered pattern. You should try your form with a hard written regex before, and then use the input one.
Follow this official guideline to create Angular 2+ forms.
answered Nov 20 '18 at 15:49
KapcashKapcash
1,2341619
Thanks! I have a question: in the first code (try-catch), nothing is happening. How do I compare a string with a regular expression?
– claudioz
Nov 20 '18 at 16:08
1
If you don't have any errors into your Regex, nothing will happen specifically. Try something like '//(', you should have an exception rising and go to the catch. For more about RegExp object, please refer to the doc : developer.mozilla.org/fr/docs/Web/JavaScript/Reference/…
– Kapcash
Nov 20 '18 at 16:12
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
- Check regex validity
You can simply catch exceptions thrown by the RegExp constructor when instanciating it.
try {
const regex = new RegExp(pattern);
} catch (error) {
// If it goes here, then the regex model is not correct
console.error(error.message)
}
- Change the visual style
You can simply use the ngClass attribute to change your input style.
If you enter the catch statement, set a style variable to change the class like so
private hasBadInput: boolean;
// [...]
catch (error) {
hasBadInput= true;
}
Then apply a specific class in that case:
<input-text [ngClass]="{'yourErrorClass': hasBadInput}"><input-text>
- Form validity
You did well using [attr.pattern], the form should automatically consider the entered pattern. You should try your form with a hard written regex before, and then use the input one.
Follow this official guideline to create Angular 2+ forms.
answered Nov 20 '18 at 15:49
KapcashKapcash
1,2341619
Thanks! I have a question: in the first code (try-catch), nothing is happening. How do I compare a string with a regular expression?
– claudioz
Nov 20 '18 at 16:08
1
If you don't have any errors into your Regex, nothing will happen specifically. Try something like '//(', you should have an exception rising and go to the catch. For more about RegExp object, please refer to the doc : developer.mozilla.org/fr/docs/Web/JavaScript/Reference/…
– Kapcash
Nov 20 '18 at 16:12
add a comment |
- Check regex validity
You can simply catch exceptions thrown by the RegExp constructor when instanciating it.
try {
const regex = new RegExp(pattern);
} catch (error) {
// If it goes here, then the regex model is not correct
console.error(error.message)
}
- Change the visual style
You can simply use the ngClass attribute to change your input style.
If you enter the catch statement, set a style variable to change the class like so
private hasBadInput: boolean;
// [...]
catch (error) {
hasBadInput= true;
}
Then apply a specific class in that case:
<input-text [ngClass]="{'yourErrorClass': hasBadInput}"><input-text>
- Form validity
You did well using [attr.pattern], the form should automatically consider the entered pattern. You should try your form with a hard written regex before, and then use the input one.
Follow this official guideline to create Angular 2+ forms.
answered Nov 20 '18 at 15:49
KapcashKapcash
1,2341619
Thanks! I have a question: in the first code (try-catch), nothing is happening. How do I compare a string with a regular expression?
– claudioz
Nov 20 '18 at 16:08
1
If you don't have any errors into your Regex, nothing will happen specifically. Try something like '//(', you should have an exception rising and go to the catch. For more about RegExp object, please refer to the doc : developer.mozilla.org/fr/docs/Web/JavaScript/Reference/…
– Kapcash
Nov 20 '18 at 16:12
add a comment |
- Check regex validity
You can simply catch exceptions thrown by the RegExp constructor when instanciating it.
try {
const regex = new RegExp(pattern);
} catch (error) {
// If it goes here, then the regex model is not correct
console.error(error.message)
}
- Change the visual style
You can simply use the ngClass attribute to change your input style.
If you enter the catch statement, set a style variable to change the class like so
private hasBadInput: boolean;
// [...]
catch (error) {
hasBadInput= true;
}
Then apply a specific class in that case:
<input-text [ngClass]="{'yourErrorClass': hasBadInput}"><input-text>
- Form validity
You did well using [attr.pattern], the form should automatically consider the entered pattern. You should try your form with a hard written regex before, and then use the input one.
Follow this official guideline to create Angular 2+ forms.
answered Nov 20 '18 at 15:49
KapcashKapcash
1,2341619
- Check regex validity
You can simply catch exceptions thrown by the RegExp constructor when instanciating it.
try {
const regex = new RegExp(pattern);
} catch (error) {
// If it goes here, then the regex model is not correct
console.error(error.message)
}
- Change the visual style
You can simply use the ngClass attribute to change your input style.
If you enter the catch statement, set a style variable to change the class like so
private hasBadInput: boolean;
// [...]
catch (error) {
hasBadInput= true;
}
Then apply a specific class in that case:
<input-text [ngClass]="{'yourErrorClass': hasBadInput}"><input-text>
- Form validity
You did well using [attr.pattern], the form should automatically consider the entered pattern. You should try your form with a hard written regex before, and then use the input one.
Follow this official guideline to create Angular 2+ forms.
answered Nov 20 '18 at 15:49
KapcashKapcash
1,2341619
answered Nov 20 '18 at 15:49
KapcashKapcash
1,2341619
answered Nov 20 '18 at 15:49
KapcashKapcash
1,2341619
answered Nov 20 '18 at 15:49
KapcashKapcash
1,2341619
1,2341619
Thanks! I have a question: in the first code (try-catch), nothing is happening. How do I compare a string with a regular expression?
– claudioz
Nov 20 '18 at 16:08
1
If you don't have any errors into your Regex, nothing will happen specifically. Try something like '//(', you should have an exception rising and go to the catch. For more about RegExp object, please refer to the doc : developer.mozilla.org/fr/docs/Web/JavaScript/Reference/…
– Kapcash
Nov 20 '18 at 16:12
add a comment |
Thanks! I have a question: in the first code (try-catch), nothing is happening. How do I compare a string with a regular expression?
– claudioz
Nov 20 '18 at 16:08
1
If you don't have any errors into your Regex, nothing will happen specifically. Try something like '//(', you should have an exception rising and go to the catch. For more about RegExp object, please refer to the doc : developer.mozilla.org/fr/docs/Web/JavaScript/Reference/…
– Kapcash
Nov 20 '18 at 16:12
Thanks! I have a question: in the first code (try-catch), nothing is happening. How do I compare a string with a regular expression?
– claudioz
Nov 20 '18 at 16:08
Thanks! I have a question: in the first code (try-catch), nothing is happening. How do I compare a string with a regular expression?
– claudioz
Nov 20 '18 at 16:08
1
1
If you don't have any errors into your Regex, nothing will happen specifically. Try something like '//(', you should have an exception rising and go to the catch. For more about RegExp object, please refer to the doc : developer.mozilla.org/fr/docs/Web/JavaScript/Reference/…
– Kapcash
Nov 20 '18 at 16:12
If you don't have any errors into your Regex, nothing will happen specifically. Try something like '//(', you should have an exception rising and go to the catch. For more about RegExp object, please refer to the doc : developer.mozilla.org/fr/docs/Web/JavaScript/Reference/…
– Kapcash
Nov 20 '18 at 16:12
add a comment |
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