Creating a large array of functions can be done by defining each function within the array individually, ensuring proper

Question

Creating a large array of functions can be done by defining each function within the array individually, ensuring proper

I attempted to define an array of functions using the code below, but encountered issues with retrieving the value of 'i' outside of the loop.

<script>
var f = []
for (var i=0; i<1000; i++){
    f[i] = function(){
        return i
    }
}
console.log(f[3]);
</script>

Instead of resorting to a brute-force method of writing 1000 lines of code to define the functions, I am curious if there are alternative approaches to tackle this problem. I faced a similar issue in Java, which is discussed in this Stack Overflow post about Array of function pointers in Java. Any insights in either Java or JS would be greatly appreciated.

javascript arrays

Answer 1

Answer №1

To ensure each function instance has its own variable, you can encapsulate it inside an immediately executed function within the loop:

var funcArray = [];
for (var index = 0; index < 1000; index++){
  (function(index){
    funcArray[index] = function(){
      return index;
    }
  })(index);
}
console.log(funcArray[3]());

See it in action: http://jsfiddle.net/Guffa/rPKss/

Answer 2

To ensure each function instance has its own variable, you can encapsulate it inside an immediately executed function within the loop:

var funcArray = [];
for (var index = 0; index < 1000; index++){
  (function(index){
    funcArray[index] = function(){
      return index;
    }
  })(index);
}
console.log(funcArray[3]());

See it in action: http://jsfiddle.net/Guffa/rPKss/

Answer 3

Answer №2

Dealing with a closure/scope problem requires locking in the value of a variable

<script>
var arr = [];
for (var x=0; x<1000; x++){
    (function(y) {
        arr[y] = function(){
            return y;
        }
    })(x); // By passing as argument to IIFE, we limit the scope
}
console.log(arr[5]);
</script>

Answer 4

Dealing with a closure/scope problem requires locking in the value of a variable

<script>
var arr = [];
for (var x=0; x<1000; x++){
    (function(y) {
        arr[y] = function(){
            return y;
        }
    })(x); // By passing as argument to IIFE, we limit the scope
}
console.log(arr[5]);
</script>

Creating a large array of functions can be done by defining each function within the array individually, ensuring proper

Answer №1

Answer №2

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