I love those short js oneliners. I'd like to know if there's something logical and elegant for:
Shorter than this preferrably ;)
var obj = {} ;
//some iterative called function
obj.prop = obj.prop===undefined?0:obj.prop++;
This will result in NaN for the first increment, which will default to 0.
obj.prop = ++obj.prop || 0;
var keyword first, though - var a = ++a || 0.undefined value. ...Nevermind, just saw your updated comment.
a variable. The answer say about variable (generic). Though the example is a property of objectA cleaner way of doing this is simply
obj.prop = obj.prop + 1 || 0;
Using the increment operator is wrong or overkill. The suffixed operator, x++, (the example in the question) should not work at all. The prefixed, ++x, leads to assigning twice (like saying x = x = x+1)
This works for both plain JS and TypeScript:
obj.prop = (obj.prop ?? 0) + 1;
To initialise to 1 obj.prop = -~obj.prop
To initialize to 0 ~~++obj.prop OR ++obj.prop | 0
Similar to I Hate Lazy's answer but avoids the double assignment as Bodgan points out
++obj.prop || (obj.prop=0)
in the global scope
++window.foo || (window.foo=0)
It is not possible to directly pass a variable to the function inc(obj.prop), because in javascript variables are passed by value, but you can pass the object itself and the name of the variable you want to increment.
Object.prototype.inc = function(n){ this[n]? this[n]++ : this[n] = 1; }
let obj = {};
obj.inc("prop");
// obj.prop == 1
You can also add the required fields to the object before
Object.prototype.has_fields = function(obj2){
for(let p of Object.keys(obj2)){
if(obj2[p].constructor == Object){
if(!this[p]) this[p] = {};
this[p].has_fields(obj2[p]);
}else{
if(!this[p]) this[p] = obj2[p];
}
}
return this;
}
let obj = {};
obj.has_fields({a:{b:{c:{d:{prop:0}}}}});
obj.a.b.c.d.prop++;
// obj.a.b.c.d.prop == 1
obj.has_fields({a:{b:{c:{d:{prop:0}}}}});
obj.a.b.c.d.prop++;
// obj.a.b.c.d.prop == 2
