RegExp.prototype.hasIndices

{{JSRef}}

The hasIndices accessor property of {{jsxref("RegExp")}} instances returns whether or not the d flag is used with this regular expression.

{{InteractiveExample("JavaScript Demo: RegExp.prototype.hasIndices")}}

const regex1 = new RegExp("foo", "d");

console.log(regex1.hasIndices);
// Expected output: true

const regex2 = new RegExp("bar");

console.log(regex2.hasIndices);
// Expected output: false

Description

RegExp.prototype.hasIndices has the value true if the d flag was used; otherwise, false. The d flag indicates that the result of a regular expression match should contain the start and end indices of the substrings of each capture group. It does not change the regex’s interpretation or matching behavior in any way, but only provides additional information in the matching result.

This flag primarily affects the return value of exec(). If the d flag is present, the array returned by exec() has an additional indices property as described in the exec() method’s return value. Because all other regex-related methods (such as {{jsxref("String.prototype.match()")}} ) call exec() internally, they will also return the indices if the regex has the d flag.

The set accessor of hasIndices is undefined. You cannot change this property directly.

Examples

There’s a more detailed usage example at Groups and backreferences > Using groups and match indices.

Using hasIndices

const str1 = "foo bar foo";

const regex1 = /foo/dg;

console.log(regex1.hasIndices); // true

console.log(regex1.exec(str1).indices[0]); // [0, 3]
console.log(regex1.exec(str1).indices[0]); // [8, 11]

const str2 = "foo bar foo";

const regex2 = /foo/;

console.log(regex2.hasIndices); // false

console.log(regex2.exec(str2).indices); // undefined

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

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