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Asney
Asked: 2020-12-22 11:13:29 +0800 CST 2020-12-22 11:13:29 +0800 CST

How to refactor excess if conditions?

  • 772

I have the following block of code:

data.split('\n').map(l => {
    if (/^videoW/.exec(l)) {
      vidConf.videoW = l.split('=')[1]
    }
    if (/^videoH/.exec(l)) {
      vidConf.videoH = l.split('=')[1]
    }
    if (/^videoT/.exec(l)) {
      vidConf.videoT = l.split('=')[1]
    }
    if (/^videoL/.exec(l)) {
      vidConf.videoL = l.split('=')[1]
    }
    if (/^time=/.exec(l)) {
      vidConf.timeImg = l.split('=')[1]
    }
    if (/^auto=/.exec(l)) {
      vidConf.videoA = l.split('=')[1]
    }
    if (/^typeP=/.exec(l)) {
      vidConf.typeP = l.split('=')[1]
    }

  })

I cut the data array by line breaks ( \n), because I extract it from an external file and perform an mapenvelope to check the existence of some variables in it through regular expressions and in this way pass the data to the vidConf variable .

How could I refactor this code avoiding so many statements if, and achieving the same result?

javascript

1 Answers

  1. Best Answer

    You could create an array with the list of "cases" ( eg: ifs) and then for each line evaluate them one by one.

    We can use someto avoid control all cases.

    some()executes the function callbackonce for each element present in arrayit until it finds one that callbackreturns a true value. If such an element is found, it some()returns true immediately.

    Example:

    let data = `videoWeight=18
videoHeight=20
time=200
auto=true`;
let vidConf = {};
let vidProps = [
  {re: /^videoW/, name: 'videoW'},
  {re: /^videoH/, name: 'videoH'},
  {re: /^videoT/, name: 'videoT'},
  {re: /^videoL/, name: 'videoL'},
  {re: /^time$/, name: 'timeImg'},
  {re: /^auto$/, name: 'videoA'},
  {re: /^typeP$/, name: 'typeP'}
]

data.split('\n').map(l => {
  let info = l.split('=');
  let name = info[0];
  let value = info[1];
  
  vidProps.some(prop => {
    if (prop.re.exec(name)) {
      vidConf[prop.name] = value;
      return true;
    }
    return false;
  });
})

console.log(vidConf);

    • 4