How can I implement RegExp in TypeScript?
My example:
var trigger = "2"
var regex = new RegExp('^[1-9]\d{0,2}$', trigger); // where I have exception in Chrome console
There are two ways by which Regex can implement in TypeScript. One of them is assigning a regular expression literal type RegExp . Copy const rExp : RegExp = /[A-C]/g; Another way of expressing regular expressions is through the RegExp constructor.
A regular expression (shortened as regex or regexp; sometimes referred to as rational expression) is a sequence of characters that specifies a search pattern in text. Usually such patterns are used by string-searching algorithms for "find" or "find and replace" operations on strings, or for input validation.
RegExp Object A regular expression is a pattern of characters. The pattern is used to do pattern-matching "search-and-replace" functions on text. In JavaScript, a RegExp Object is a pattern with Properties and Methods.
Advertisements. The "regexp" command is used to match a regular expression in Tcl. A regular expression is a sequence of characters that contains a search pattern. It consists of multiple rules and the following table explains these rules and corresponding use.
I think you want to test
your RegExp in TypeScript, so you have to do like this:
var trigger = "2",
regexp = new RegExp('^[1-9]\d{0,2}$'),
test = regexp.test(trigger);
alert(test + ""); // will display true
You should read MDN Reference - RegExp, the RegExp
object accepts two parameters pattern
and flags
which is nullable(can be omitted/undefined). To test your regex you have to use the .test()
method, not passing the string you want to test inside the declaration of your RegExp!
Why test + ""
?
Because alert()
in TS accepts a string as argument, it is better to write it this way. You can try the full code here.
You can do just:
var regex = /^[1-9]\d{0,2}$/g
regex.test('2') // outputs true
In TypeScript, the declaration is something like this:
const regex : RegExp = /.+\*.+/;
Using RegExp constructor:
const regex = new RegExp('.+\\*.+');
const regex = /myRegexp/
console.log('Hello myRegexp!'.replace(regex, 'World')) // = Hello World!
The Regex literal notation is commonly used to create new instances of RegExp
regex needs no additional escaping
v
/ regex / gm
^ ^ ^
start end optional modifiers
As others sugguested, you can also use the new RegExp('myRegex')
constructor.
But you will have to be especially careful with escaping:
regex: 12\d45
matches: 12345
Extra excape because it is part of a string
v
const regex = new RegExp('12\\d45')
const equalRegex = /12\d45/
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