Speedtest

JavaScript RegExp objects are stateful when they have the global or sticky flags set (e.g., /foo/g or /foo/y). They store a lastIndex from the previous match. Using this internally, test() can be used to iterate over multiple matches in a string of text (with capture groups).

SpeedtestGoogle

To get more information (but with slower execution), use the exec() method. (This is similar to the String.prototype.match() method.)

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As with exec() (or in combination with it), test() called multiple times on the same global regular expression instance will advance past the previous match.

test中文

The string against which to match the regular expression. All values are coerced to strings, so omitting it or passing undefined causes test() to search for the string "undefined", which is rarely what you want.

Use test() whenever you want to know whether a pattern is found in a string. test() returns a boolean, unlike the String.prototype.search() method (which returns the index of a match, or -1 if not found).

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

test什么意思

The test() method of RegExp instances executes a search with this regular expression for a match between a regular expression and a specified string. Returns true if there is a match; false otherwise.

When a regex has the global flag set, test() will advance the lastIndex of the regex. (RegExp.prototype.exec() also advances the lastIndex property.)

Further calls to test(str) will resume searching str starting from lastIndex. The lastIndex property will continue to increase each time test() returns true.