CODEWITHSUNDEEP
javascript
Salvador Dali
Salvador Dali

Reputation: 222571

Any way to simplify long if else statement with < in conditions?

I have the following part of code, which I do not really like:

if (a < 2){
    b = 'somethingX';
} else if (a < 4){
    b = 'somethingY';
} else if (a < 6){
    ....;
} else {
    b = 'somethingZ';
}

I have something like 20 such if else statements and all of them consist of (a < SomeNumber) conditions. Result I am assigning to b can is not a function of a and a < someNumber is not in a regular interval. I would like to simplify them, but can not come up with an adequate solution.

If I would have (a === SomeNumber) I would be able to do this easily with creating an object and accessing the value from this object (something similar to this), but here I have < sign. Is there any approach?

P.S. please do not suggest changing this to switch. I would like to make it easier to read, and based on my subjective opinion reading switch is on the same level as if else.

P.S.2 people asked the reason for this logic. Basically I have a thin client which returns code for error messages. They grouped in some particular way. For example everything from 1 to 8 is because there is some problem with a user. From 9 to 21 because the key is not correct. Sometimes I do not need to notify a user the exact message, so because of the grouping I can just tell generic message. Why my server is not sending the message? It is as thin as possible, so sending 7 is better then a big string.

Upvotes: 1

Views: 458

Answers (2)

GameAlchemist
GameAlchemist

Reputation: 19294

Best way to handle it would be to use an array with the steps and associated values. You also need a default value : 

var default = 'aValue';
var steps   = [2, 'something', 6, 'anotherThing', 8, 'this', 10, 'that', ... ];

Then define a function that uses this array

function findSmallestMatch(val, default, steps) {
     for (var i=0; i<steps.length; i+=2) if (val<steps[i]) return steps[i+1];
     return default;
}

Use it with :

var res = findSmallestMatch ( 5, default, steps );  // returns 'anotherThing

Edit : If you know your input is a positive integer within a 'reasonable' range, you can pre-fill a map with the values :

var default = 'aValue';
var steps   = [2, 'something', 6, 'anotherThing', 8, 'this', 10, 'that', ... ];
var matchMap = [];
for (var i=0; i<maximumValue; i+=1) 
     matchMap[i] = findSmallestMatch(i, default, steps);

later you can use simply with : 

var res = matchMap[value];

Upvotes: 4

xdazz
xdazz

Reputation: 160853

You could do something like this:

var data = [[2, 'somethingX'], [4, 'somethingY'], ......];
var b = 'somethingZ'; // default value

for (var i=0; i < data.length; i++) {
  if (a < data[i][0]) {
     b = data[i][1];
     break;
  }
}

Upvotes: 2

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