Three supported flags represent matching modes, as follows:
| Flag | Mode | Meaning |
|---|---|---|
| g | global mode | match all string instead of stopping after the first match is found. |
| i | case-insensitive mode | the pattern and the string are ignored when determining matches. |
| m | multiple line mode | continue looking for matches after reaching the end of one line of text. |
| y | sticky mode | only look at the string contents beginning at lastIndex. |
| u | Unicode mode | Unicode is enabled. |
A regular expression is created using a combination of a pattern and these flags to produce different results.
Match all instances of "at" in a string.
let pattern1 = /at/g;
Match the first instance of "bat" or "cat", regardless of case.
let pattern2 = /[bc]at/i;
Match all three-character combinations ending with "at", regardless of case.
let pattern3 = /.at/gi;