I still use javascript and not typescript.
I'm quite happy to use == everywhere in my code.
=== would be good if you use typescript and are sure of all your types.
TypeScript gives you type notation, so you know what types your variables are. Thus === should be redundant, because you shouldn't need to type check.
With JavaScript types are not as obvious. Comparing with == is error prone because it will try to coerce your variables to be the same type, whereas with === it won't. Sometimes in JS types matter, so using === is preferable so you don't end up assigning a string to a number or vice versa.
In javascript I want to compare 4 == "4" and get true.
In typescript you should get and error before compile if you try to compare 4 == "4" I guess...
When I saw the === the first time, I thought it was for "deep" comparison of objects :-)
ie: {a:1, b:2} === {b:2, a:1} should be true.
So I guess we still have no answer why to use === rather than == in everyday JS code.
I've never had a reason to say "types does matter" - mysql and json is happy saving a string to a number and vice versa. Displaying entry fields or text in html as well.
I guess in a accounting environment maybe? Negatives, decimals, power of 10, etc.. You would want to make 100% sure you have a number, and if user type 10e2.123 you would need to convert to 1000.12 before saving?
I see I use parseInt if I want to add numbers.
ie:
return this.meritList.reduce( (accum,item) => accum + parseInt(item.point),0)
The question was why to ever use == rather than the ===.
You're saying you never use === in JavaScript? Do you not fall foul of the problem where 3+3 is not the same as '3'+3? Or that '0' == 0 but 0 == false and '0' == true?
I still use javascript and not typescript.
I'm quite happy to use == everywhere in my code.
=== would be good if you use typescript and are sure of all your types.
I'm not sure this reasoning is sound.
TypeScript gives you type notation, so you know what types your variables are. Thus
===should be redundant, because you shouldn't need to type check.With JavaScript types are not as obvious. Comparing with
==is error prone because it will try to coerce your variables to be the same type, whereas with===it won't. Sometimes in JS types matter, so using===is preferable so you don't end up assigning a string to a number or vice versa.In javascript I want to compare 4 == "4" and get true.
In typescript you should get and error before compile if you try to compare 4 == "4" I guess...
When I saw the === the first time, I thought it was for "deep" comparison of objects :-)
ie: {a:1, b:2} === {b:2, a:1} should be true.
So I guess we still have no answer why to use === rather than == in everyday JS code.
I've never had a reason to say "types does matter" - mysql and json is happy saving a string to a number and vice versa. Displaying entry fields or text in html as well.
I guess in a accounting environment maybe? Negatives, decimals, power of 10, etc.. You would want to make 100% sure you have a number, and if user type 10e2.123 you would need to convert to 1000.12 before saving?
I see I use parseInt if I want to add numbers.
ie:
return this.meritList.reduce( (accum,item) => accum + parseInt(item.point),0)
And that's about it.
The question was why to ever use
==rather than the===.You're saying you never use
===in JavaScript? Do you not fall foul of the problem where3+3is not the same as'3'+3? Or that'0' == 0but0 == falseand'0' == true?I did a quick grep - and I see there is some place where I use ===
if (!response.constructor === Array)
if (this.photoPath === undefined)
But I use == much more frequently
Never realised that 0 == false and '0' == true - that is a nasty one.
But I've never when debugging, had an error related to == vs ===
Lucky or dumb, or dumb luck I guess?