Use a variable as a regex to find all matches in a string
Often I have to use a value from a variable and not a fixed string inside a regular expression. For example if I wanted to iterate over the English alphabet and find the number of occurrences of each letter inside a string, I had to do something like the following:
var testString = "Lorem ipsum dolor sit amet, consetetur sadipscing elitr.";
var matches = testString.match(/a/g).length;
// do this for all the remaining letters
the previous example would work and would find all occurrences of “a”.
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