How to retrieve the value from an array without index

Question

[["Django UnChainers","AA-24010"],["General","AA-26191"]]

I have one array in above form. I want to retrieve all the value with prefix AA (which are in the second position). Is there any way where I can fetch the value by passing prefix?.

I know the way where I can get the value by passing index but may be tomorrow index can get change so is it possible to fetch the value by passing prefix?

• UnholySheep: Iterate through the array(s) and check whether the entry startsWith or contains "AA"?

Answer 1

In case OP wants a function to do this.

function(arr, pattern){
 return arr.map(function(x){
 return x.filter( word => ~ word.indexOf(pattern))
 }); 
}

var arr = 
[ [ "Django UnChainers", "AA-24010" ], [ "General", "AA-26191" ]];
var list = arr.map(function(x){
 if(~(x[1].indexOf('AA'))){
 return x[1];
 }
});
console.log(list);

In case the index changes in future, iterate through each string and check for the "AA" string. Check the below code.

var arr = 
 [ [ "Django UnChainers", "AA-24010" ], [ "General", "AA-26191" ]];
 var list = arr.map(function(x){
 return x.filter( word => ~ word.indexOf('AA'))
 });
 console.log(list);

• RomanPerekhrest: but may be tomorrow index can get change
• Hassan Imam: In that case we have to iterate through each element in the array, which won't be a problem.
• RomanPerekhrest: which won't be a problem - prove it
• Yoshi: @RomanPerekhrest Just make it a function and extract the argument, it's really not a lot of magic.

Answer 2

this is shorter

var = [nested array]
a.filter(x => x[1].startsWith('AA'))
//in case you are not sure about the index 
a.filter(x => x.filter(y => y.startsWith('AA').length > 0))

• RomanPerekhrest: but may be tomorrow index can get change
• Hamuel: I have added which will increase the running time but if the index change it will not be affected.