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[javascript/en] Added for/in loop JavaScript

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more explanation about for/in java script.
This commit is contained in:
Raphael Nascimento 2015-10-06 23:44:30 -03:00
parent fe52573118
commit f1711ddd4c
1 changed files with 14 additions and 1 deletions
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15
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@ -218,13 +218,26 @@ for (var i = 0; i < 5; i++){
// will run 5 times // will run 5 times
} }
//The For/In statement loops through the properties of an object: //The For/In statement loops iterates over every property across the entire prototype chain
var description = ""; var description = "";
var person = {fname:"Paul", lname:"Ken", age:18}; var person = {fname:"Paul", lname:"Ken", age:18};
for (var x in person) { for (var x in person) {
description += person[x] + " "; description += person[x] + " ";
} }
//If only want to consider properties attached to the object itself,
//and not its prototypes use hasOwnProperty() check
var description = "";
var person = {fname:"Paul", lname:"Ken", age:18};
for (var x in person) {
if( person.hasOwnProperty( x ) ) {
description += person[x] + " ";
}
}
//for/in should not be used to iterate over an Array where the index order is important.
//There is no guarantee that for/in will return the indexes in any particular order
// && is logical and, || is logical or // && is logical and, || is logical or
if (house.size == "big" && house.colour == "blue"){ if (house.size == "big" && house.colour == "blue"){
house.contains = "bear"; house.contains = "bear";