如何使大型的if / else语句更严格？

Question

I have something like the following:

if (value === section1) {
  runChecks(checkObject[1].value1, checkObject[1].value2, leftAlign);
} else if (value === section2) {
  runChecks(checkObject[2].value1, checkObject[2].value2, rightAlign);
} else if (value === section3) {
  runChecks(checkObject[3].value1, checkObject[3].value2, leftAlign);
} else if (value === section4) {
  runChecks(checkObject[4].value1, checkObject[4].value2, rightAlign);
} else if (value === section5) {
  runChecks(checkObject[5].value1, checkObject[5].value2, leftAlign, true);
} else if (value === section6) {
  runChecks(checkObject[6].value1, checkObject[6].value2, rightAlign);
} ...

It runs longer than this as there's a large number of pre-defined values.

Example of checkObject:

  var checkObject = [{
    value1: '19.1%',
    value2: '19.1%',
  }, {
   value1: '19.1%',
    value2: '19.1%',
  }, {
   value1: '19.1%',
    value2: '19.1%',
  }, ...

I want to break it down and make it more efficient but given there's variations on the data being passed to runChecks() I'm not sure how to manage it.

Answer 1

Use switch!

switch(value){
    case section1:
        runChecks(checkObject[1].value1, checkObject[1].value2, leftAlign);
    break
    case section2:
      runChecks(checkObject[2].value1, checkObject[2].value2, rightAlign);
    break
    ... 
}

It's not really any shorter than using if / else if / else but it looks cleaner.

Answer 2

Actually, you can just use a for loop.

Create an array object containing all the sections. (I will provide the real javascript later. But here is some half-pseudocode).

   var counter = 1;
    var N = something;
    var sectionArray = {section1, section2, section3, ..., sectionN};


   for(;counter<N; counter++){

   if(value === sectionArray[counter]){
  runChecks(checkObject[counter].value1, checkObject[counter].value2, rightAlign);
break;
   }

}

Answer 3

One way would be to use loop for instance.

let sections = ['section1', 'section2', 'section3', 'section4'];

for (let i = 0; i < sections.length; i++) {
    if (value === sections[i]) {
        runChecks(checkObject[1].value1, checkObject[1].value2, leftAlign);
    }
}

Answer 4

You could use some with a short circuit if the value is found.

[section1, section2, section3, section4, section5, section6].some((v, i) => {
    if (v === value) {
        runChecks(
            checkObject[i + 1].value1,
            checkObject[i + 1].value2,
            i % 2 ? rightAlign : leftAlign
            i === 5 || undefined
        );
        return true;
    }
});

Answer 5

Couldn't you iterate over the array? You might need to add all information that you require in the runChecks function though (I added mybool, since I wasn't sure where this true is coming from).

checkObject.forEach(function(value, index) {
  let alignment = index % 2 == 0 ? leftAlign : rightAlign;
  runChecks(value.value1, value.value2, alignment, value.mybool);
});

Answer 6

There are too many repeating parts in your code. I would do it this way.

var scs = [null, section1, section2, section3, section4, section5, section6];
var si = scs.indexOf(value);
var align = ((si&1)==1) ? leftAlign : rightAlign;
runChecks(checkObject[si].value1, checkObject[si].value2, align, si==5);