I want to create a regex pattern which should be able to search through an array.
Let's say :
var arr = [ "first", "second", "third" ];
var match = text.match(/<arr>/);
which should be able to match only
<first> or <second> or <third> ......
but should ignore
<ffirst> or <dummy>
I need an efficient approach please .
Any help would be great . Thanks
| and create an instance of RegExp.function quoteSpecial(str) { return str.replace(/([\[\]^$|()\\+*?{}=!.])/g, '\\$1'); }
var arr = [ "first", "second", "third", "fo|ur" ];
var re = new RegExp('<(?:' + arr.map(quoteSpecial).join('|') + ')>');
//=> /<(?:first|second|third|fo\|ur)>/
then use this RegExp object:
'<first>'.match(re); // ["<first>"]
'<ffirst>'.match(re); // null
'<dummy>'.match(re); // null
'<second>'.match(re); // ["<second>"]
'<fo|ur>'.match(re); // ["<fo|ur>"]
You should search for a specific word from a list using (a|b|c).
The list is made from the arr by joining the values with | char as glue
var arr = [ "first", "second", "third" ];
var match = text.match(new RegExp("<(?:"+arr.join("|")+")>")); //matches <first> <second> and <third>
Note that if your "source" words might contain regular expression's preserved characters - you might get into trouble - so you might need to escape those characters before joining the array
A good function for doing so can be found here:
function regexpQuote(str, delimiter) {
return String(str)
.replace(new RegExp('[.\\\\+*?\\[\\^\\]$(){}=!<>|:\\' + (delimiter || '') + '-]', 'g'), '\\$&');
}
so in this case you'll have
function escapeArray(arr){
var escaped = [];
for(var i in arr){
escaped.push(regexpQuote(arr[i]));
}
return escaped;
}
var arr = [ "first", "second", "third" ];
var pattern = new RegExp("<(?:"+escapeArray(arr).join("|")+")>");
var match = text.match(pattern); //matches <first> <second> and <third>
arr isn't containing | and similar functional characters before compiling this way.