Question 397063 in Javascript Question posted in
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Javascript – Utilizing array items as an entire case in a switch statement

I would like to generate cases in a switch statement from an array. Here is how the array is generated:

pointObjects = [];

for (var i = 0; i < 2; i++) {
    // Generate cases.
    var url;
    var pointObject = 
        {
            case: 'Placeholder',
            url: 'google.com'
        }

pointObjects.push(pointObject);
}

Thus, pointObjects[0] returns:

{
    case: 'Placeholder'
    url: 'google.com
}

I’d like to render these each within a switch statement, so it will act the same as the code below:

                    click: function(event) {
                        var seriesName = this.name;
                        var url;

                        // Attaches the query link to the respective slice.
                        switch (seriesName) {
                            case 'Placeholder':
                                url = 'google.com';
                                break;
                            case 'Placeholder':
                                url = 'google.com';
                                break;
                            default:
                                url = '#';
                        }

                        // Opens the query in a new tab
                        if (url !== '#') {
                            window.open(url, '_blank');
                        }
                    }

I tried the following code but it says that pointObjects is an unexpected identifier:

                        switch (seriesName) {
                            pointObjects.forEach(obj => {
                            case obj.case:
                                url = obj.url;
                                break;
                            });
                            default:
                                url = '#';
                        }
Tags:

2

Answers


  1. 0

    The only things that you can put inside of a switch statement are case clauses and default clauses. Anything else, such as trying to call pointObjects.forEach, is illegal syntax. As a result, you cannot dynamically change the number of switch statements. Instead, you will need to write your code using other techniques.

    For example, a for loop:

    click: function(event) {
  const seriesName = this.name;
  let url = "#";
  for (const obj of pointObjects) {
    if (obj.case === seriesName) {
      url = obj.url;
      break;
    }
  }

  if (url !== '#') {
    window.open(url, '_blank');
  }
}

    Or using the .find method on arrays:

    click: function(event) {
  const seriesName = this.name;
  const obj = pointObjects.find(obj => obj.case === seriesName); 
  const url = obj?.url ?? '#';

  if (url !== '#') {
    window.open(url, '_blank');
  }
}

    If changing pointObjects is an option, you could also turn it into an object and do a lookup by key:

    const pointObjects = {
  Placeholder: 'google.com'
}
// ...

click: function(event) {
  const url = pointObjects[this.name] ?? '#'

  if (url !== '#') {
    window.open(url, '_blank');
  }
}
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  2. 0

    You don’t have to use switch/case. Neither do you have to use an array. How about the following?

    const 
      input = [['case1','case1.com'],['case2','case2.com'],['case3','case3.com']],
      output = Object.fromEntries(input),
      getURL = caseName => output[caseName] ?? '#';

//Giving rise to
console.log( output );

//instead of using switch you can simply use getURL(caseName);
let seriesName = '';
console.log( getURL( seriesName ) );

seriesName = 'case3';
console.log( getURL( seriesName ) );
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