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search text in array using regex in javascript

I am very new to making search text in array some elements in array are in rangers i.e it cant be anything after certain text in this AA and A regex and I have multi-dimensional array and I want search text in each array . So I wrote something like this.I put AA* in array so only first 2 character should match and A* for only one character match.

arr = [
     ["AA*","ABC","XYZ"] ,
    ["A*","AXY","AAJ"]
    ]
    var text = "AA3";
    for ($i=0; $i<arr.length; $i++ ){
        var new_array = [];
        new_array = arr[$i];
        new_array.filter(function(array_element) {
              var result = new RegExp(array_element).test(text);
              
              if( result == true){
                console.log(arr[$i]);
          } 
            
          });
    }

So what i want is when text = "AA3" or anything after double A AA[anything] and the output should be first array which is ["AA*","ABC","XYZ"] but I am getting both array as output and when text = "A3" then output should be second array which is ["A*","POI","LKJ"] but I am getting both array.But if text = "ABC" or text = "AAJ" then it should output first array or second array respectively.I dont know anything about how to write regex or is there anyway I can implement this using any other method. Thanks in advance any advice will be helpful.

about 4 years ago · Juan Pablo Isaza

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Answer 1 · 2022-07-03T00:35:36.981Z

Summary

In short, the issue is "*"! The * found in the members of the set array is why you're getting the same array each time.

Detailed Info

Regexp is a one concept most developers find hard to understand (I am one of such btw 😅).

I'll start off with an excerpt intro to Regexp on MDN

Regexp are patterns used to match character combinations in strings - MDN

With that in mind you want to understand what goes on with your code. When you create a Regex like /A*/ to test "AA3", what would be matched would be A, AA, etc. This is a truthy in javascript. You would want a more stricter matching with ^ or $ or strictly matching a number with \d.

I rewrote your code as a function below:

arr = [
    ["AA*", "ABC", "XYZ"],
    ["A*", "AXY", "AAJ"],
];

findInArray(arr, "AA3") // prints both array
findInArray(arr, "AAJ") // prints second array
findInArray(arr, "ABC") // prints first array

function findInArray(array, value) {
    return array.filter((subArray) =>
        subArray.some((item) => {
            const check = new RegExp(value);
            return check.test(item);
        })
    );
}

Answer 2 · 2022-07-03T00:35:36.990Z

Problem

The problem lies in the fact you use each of the strings as a regex.

For a string with a * wildcard, this evaluates to zero or more matches of the immediately preceding item, which will always be true.
For a string consisting solely of alphanumerics, this is comparing a string to itself, which similarly will always give true.
For strings containing characters that constitute the regex's syntax definition, this could result in errors or unintended behavior.

MDN article on RegExp quantifiers

Rewrite

Assumptions:

The value with a * wildcard is always only at the 0^th position,
There is only one such wildcard in its string,
The question mentions that for text = 'AAJ' only the 2^nd array shall be returned, but both the AA* from the 1^st array and AAJ from the 2^nd would seem to match this text.
As such, I assume the wildcard can only stand for a number (as other examples seem to suggest).

Code:

const abc = (arrs, text) => {
  return arrs.filter(arr => {
    const regex = new RegExp(`^${arr[0].replace('*', '\\d+')}$`);
    return regex.test(text) || arr.includes(text);
  })
}



const arr = [
  ["AA*", "ABC", "XYZ"],
  ["A*", "AXY", "AAJ"]
];

console.log(
`1=[${abc(arr, "AA3")}]
2=[${abc(arr, "ABC")}]
3=[${abc(arr, "AAJ")}]`);

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