javascript prüfen, ob Array-Schlüssel

Question

var place = [] 

place[0] = "Sant Marti de Canals"; 
place[1] = "Catalonia"; 
place[3] = ""; 
place[4] = "Spain"; 

placeTitle = place.join(","); 

Stromausgang gesetzt wird, ist "Sant Marti de Canals, Katalonien ,,, Spanien"

wie kann es "Sant Marti de Canals, Katalonien, Spanien" sein

Answer 1

Das Schreiben Ihres eigenen Codes kann helfen

var place = [] 

place[0] = "Sant Marti de Canals"; place[1] = "Catalonia"; place[3] = ""; place[4] = "Spain"; 

var placeTitle =''; 
for(var test in place) { 
    placeTitle += place[test]!=''?place[test]+',':''; 
} 
placeTitle = placeTitle.substr(0,placeTitle.length-1) 

Answer 2

Sie können auch eine Filterfunktion definieren, die in vielen anderen Situationen nützlich ist.

Array.prototype.filter = function(p) { 
    var a = []; 
    p = p || function (x) {return x;} 
    for (var i = 0; i<this.length; ++i) { 
     if (p(this[i])) { 
      a.push(this[i]); 
     } 
    } 
    return a; 
} 

... 

placeTitle = place.filter().join(', '); 

Answer 3

placeCopy=[]; 
for(var i=0;i<place.length;i++){ 
    if(typeof place[i] != 'undefined' && place[i].length > 0){ 
    placeCopy.push(place[i]); 
    } 
} 
placeTitle = placeCopy.join(",");