Hi I have a "persons" Object that contains four "person" Objects
[Object, Object, Object, Object]
In turn, each these "person" Objects contain keys and values. How do I access these values in Javascript? Trying this to access their "name" field, for example, doesn't work:
for(var person in data.persons) {
var nameList = nameList + person.name;
}
I'm a JS newbie. Thanks!
Since that your persons object is actually an Array, you can access it with a simple for, but iterating with an index variable, like this:
var nameList = '';
for (var i=0, person; person = data.persons[i]; i++) {
nameList += person.name;
}
or eventually, like this:
var nameList = '';
for (var i=0; i < data.persons.length; i++) {
nameList += data.persons[i].name;
}
What you're doing there is to iterate over the indexes, so your person variable holds an index number, not a person object:
for(var person in data.persons) {
// person will be 0, 1, 2, 3...
// by the way you can still do:
nameList += data.persons[person].name;
}
undefined when it gets to the end. The problem with this approach is if there is a falsy value partway through the array, it will stop and not continue past it. Using the length is much better.
forEach (not each) is not guaranteed to be supported by all the browsers and JS engines.You cannot use a for-in loop with an array. Use a for loop instead with a counter.
for (var i = 0; i < data.persons.length; i++) {
var person = data.persons[i];
var nameList = nameList + person.name;
}
for loop, this can lead to nasty bugs when combined with closures and variable hoisting.Mb it because of your syntax ? Try that and show your output:
var nameList = '';
var test = {name: 'Joe'};
var persons = [test, test];
persons.forEach(function(v, i){
console.log(v.name);
console.log("index = " + i);
nameList = nameList + v.name;
});
console.log(nameList);
P.s edit and check, all ok!
