Dynamic if statement using string variable

Question

I have an object in JavaScript that starts by looking like this:

variable = {1: 'No', 2: 'No', 3: 'No'}

and it dynamically changes based on user and updates to look like this, for example:

variabel = {1: 'Yes', 2: 'No', 3: 'Yes'}

I now want to dynamically build an if statement for any keys that have a yes to be like this:

if (feature.properties.1.indexOf(variable.1)!=-1 && feature.properties.3.indexOf(variable.3)!=-1)

Is there a way to do this? I tried looping over the object to dynamically build a string statement and then attempted to unstring it to be used in the if statement but had no luck. Any help is much appreciated.

What is in feature.properties... And why are you using strings for booleans? — Sjoerd de Wit
– Sjoerd de Wit, Commented May 11, 2015 at 14:45
feature.properties is coming from a json object. And I am not sure about the boolean vs string, does it matter? — EvanL
– EvanL, Commented May 11, 2015 at 14:54
So are you trying to test if, for every own property of feature.properties, there is a same–named property of variable whose value is a substring of the feature.properties value? — RobG
– RobG, Commented May 11, 2015 at 15:00

danronmoon · Accepted Answer · 2015-05-11 14:41:57Z

2

var success = true;

for (var i in variable) {
   if (feature.properties[i].indexOf(variable[i]) === -1) {
       success = false;
       break;
   }
}

// evaluate success here

answered May 11, 2015 at 14:41

danronmoon

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Comments

ssube · Accepted Answer · 2015-05-11 14:52:22Z

1

You can take the properties present in your desired comparison target (called "reference" for simplicity) and check the corresponding properties in the feature. If a property exists in the reference but not the feature, this will consider the validation a failure.

var reference = {
  1: 'Yes',
  2: 'No',
  3: 'Yes'
};

var feature1 = {
  properties: {
    1: 'Yes',
    3: null
  }
};

var feature2 = {
  properties: {
    1: 'Yes',
    3: 'Yes'
  }
};

function compareReference(ref, feature) {
  var props = feature.properties;
  return Object.keys(ref).reduce(function(prev, key) {
    console.log('comparing', key, ref[key], props[key], prev);
    if (ref[key] === 'Yes') {
      // Only compare yes values
      return prev && props[key] === 'Yes'; 
    } else {
      return prev;
    }
  }, true);
}

document.getElementById('r1').textContent = '' + compareReference(reference, feature1);
document.getElementById('r2').textContent = '' + compareReference(reference, feature2);

<div id="r1"></div>
<div id="r2"></div>

edited May 11, 2015 at 14:52

answered May 11, 2015 at 14:46

ssube

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4 Comments

RobG Over a year ago

Shouldn't the second object return true? every might be a better choice than reduce.

EvanL Over a year ago

I was originally trying to build a string statement to just insert into the if statement (unstringed) but can't figure out how to make the string not a string.

ssube Over a year ago

@EvanL If you already have an object representing the desired options and an object with the actual options, you can replace the if condition with a function call. Building and evaluating a string at runtime is poor practice, since it's very difficult to debug and can cause other problems.

EvanL Over a year ago

Okay, I will try that. Thanks. (I am a bit new to using javascript if that is not obvious)

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