Having trouble getting the .push() method in JavaScript to function correctly

I've encountered an issue while trying to develop a function that iterates through each item in an array and records the index of a specific item when found. In this particular function, whenever the item 'contraband' is detected during the loop, the program should note its index by using the .push() method to add it to an array named 'contrabandIndexes'. However, there seems to be an error within the command or another section of the code since executing the function with a sample array results in an empty output.

Can you help pinpoint where I may have made a mistake?

function scan(freightItems) {
    let contrabandIndexes = [];
    freightItems.forEach(function(freightItem, index) {
        if (freightItem === 'contraband') {
            contrabandIndexes.push(index);
        }
    });
    return contrabandIndexes;
}

const indexes = scan(['dog', 'contraband', 'cat', 'zippers', 'contraband']);
console.log('Contraband Indexes: ' + indexes);

Answer №1

The forEach Array method includes the index parameter along with each element, allowing you to access and manipulate the index value within the loop. This can be useful for tasks like appending specific indexes to an array such as contrabandIndexes.

function checkCargo(freightItems) {
    const contrabandIndexes = [];
    freightItems.forEach(function(item, index) {
        if (item === 'contraband') {
            contrabandIndexes.push(index);
        }
    });
    return contrabandIndexes;
}

const result = checkCargo(['dog', 'contraband', 'cat', 'zippers', 'contraband']);
console.log('Contraband Indexes: ' + result);

In this snippet, there is no need to declare let contrabandIndexes = []; outside of the function since it is already initialized within the scope of the checkCargo function.

Answer №2

Upon reviewing the insights shared by others, it is recommended that you take a look at the following:

function SecurityAgent(){
  this.staff = [...arguments]; this.prohibitedItems = []; this.houses = []; this.retained = [];
  this.inspect = array=>{
    const s = this.staff, h = this.houses, p = this.prohibitedItems;
    array.forEach((v, i)=>{
      if(s.indexOf(v) === -1){
        h.push({[v]:i});
      }
      else{
        p.push({[v]:i});
      }
    });
    return this;
  }
  this.retainHousedItems = ()=>{
    const h = this.houses;
    h.forEach(o=>{
      for(let i in o){
        this.retained.push(i);
      }
    });
    h.splice(0);
    return this;
  }
  this.clearProhibitedItems = ()=>{
    this.prohibitedItems.splice(0);
    return this;
  }
}
const sa = new SecurityAgent('gun', 'knife', 'noose');
sa.inspect(['noose', 'gun', 'dog', 'gun', 'cat', 'zippers', 'knife', 'phone']);
console.log(sa.houses); console.log(sa.prohibitedItems); sa.retainHousedItems(); console.log(sa.retained);

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