How to make a variable be a condition?-CodePudding

I have been trying to make a variable have two values/be a condition. It's fine if this is not possible, but I would like to not have to type 68 || 39 every time I would like to check. I have tried var left = 68 || 39 and var left = 68 && 39, but neither of those work. The variable is to check an event.keyCode number. I am trying to make my first game-in-javascript. Is this possible and if so how?

CodePudding user response：

I don't believe there is a way to make a variable be a condition but what you can do is define a method that checks if the value is 69 or 39.

For example:

function valueIs69or39(valueToCheck) {
    return valueToCheck == 69 || valueToCheck == 39;
}

now you can just use if (valueIs69or39(value)) to check, and you can shorten the method name to make it easier to type.

Hope this helps!

CodePudding user response：

If you have multiple values that fulfil a condition what you really want to do is use a collection of values as your variable, instead of a single value. i.e. An array (or Set, or Map, there are many higher order collection types that are designed for different purposes)

Something like this:

let allowedValues = [ 69, 39 ];

You would then use a method to check those values:

function testValue( value ) {
    return allowedValues.includes(value)
}

Same thing with a Set (you might use a Set because it guarantees each element only appears once):

let allowedValues = new Set([ 39, 68 ])

function testValue(value) {
    return allowedValues.has(value)
}

Same thing but with a Set that is immutable (the allowed values cannot be changed dynamically):

function testValue(value) {
    const allowedValues = new Set([ 39, 68 ])
    return allowedValues.has(value)
}

console.log(testValue(10))
console.log(testValue(39))