Added default value field to toNumber function

[kapilkumar9395]

Modified toNumber method to have two parameters

1. value
2. defaultValue - when given value can't be converted into number it will return the default value

[Trott]

Needs tests and docs.

Doesn't seem like a great API function signature. If I look at code and see _.toNumber(something), that's clear. If I see _.toNumber(something, somethingElse), I'm not sure what is going on. I'm not sure about the performance implications, but it is probably better to use an options object in this case: _.toNumber(something, {defaultValue: 0})

[kapilkumar9395]

@Trott thanks for the input. I have made the necessary changes

[Trott]

@Trott thanks for the input. I have made the necessary changes

I'm not a lodash maintainer or anything, so bear that in mind, but I would imagine that the tests should be added to test/number-coercion-methods.spec.js rather than creating a separate test file just for additional toNumber() tests. That also raises the question of whether symmetric changes should be made to the API of toFinite(), toInteger(), and toSafeInteger(). But those never return NaN so I'm not sure it makes sense.

That in turn raises the issue of whether this API adjustment makes sense. It seems like it would typically be used to return 0 instead of NaN, but that's already what toFinite() does, and toFinite() has the added bonus of returning usable values for Infinity and -Infinity.