Since Javascript 1.7 there is an Iterator object, which allows this:
var a={a:1,b:2,c:3};
var it=Iterator(a);
function iterate(){
try {
console.log(it.next());
setTimeout(iterate,1000);
}catch (err if err instanceof StopIteration) {
console.log("End of record.\n");
} catch (err) {
console.log("Unknown error: " + err.description + "\n");
}
}
iterate();
is there something like this in node.js ?
Right now i'm using:
function Iterator(o){
/*var k=[];
for(var i in o){
k.push(i);
}*/
var k=Object.keys(o);
return {
next:function(){
return k.shift();
}
};
}
but that produces a lot of overhead by storing all the object keys in k
.
This question is related to
javascript
node.js
iterator
adjust his code:
Object.prototype.each = function(iterateFunc) {
var counter = 0,
keys = Object.keys(this),
currentKey,
len = keys.length;
var that = this;
var next = function() {
if (counter < len) {
currentKey = keys[counter++];
iterateFunc(currentKey, that[currentKey]);
next();
} else {
that = counter = keys = currentKey = len = next = undefined;
}
};
next();
};
({ property1: 'sdsfs', property2: 'chat' }).each(function(key, val) {
// do things
console.log(key);
});
For simple iteration of key/values, sometimes libraries like underscorejs can be your friend.
const _ = require('underscore');
_.each(a, function (value, key) {
// handle
});
just for reference
Also remember that you can pass a second argument to the .forEach()
function specifying the object to use as the this
keyword.
// myOjbect is the object you want to iterate.
// Notice the second argument (secondArg) we passed to .forEach.
Object.keys(myObject).forEach(function(element, key, _array) {
// element is the name of the key.
// key is just a numerical value for the array
// _array is the array of all the keys
// this keyword = secondArg
this.foo;
this.bar();
}, secondArg);
I'm new to node.js (about 2 weeks), but I've just created a module that recursively reports to the console the contents of an object. It will list all or search for a specific item and then drill down by a given depth if need be.
Perhaps you can customize this to fit your needs. Keep It Simple! Why complicate?...
'use strict';
//console.log("START: AFutils");
// Recusive console output report of an Object
// Use this as AFutils.reportObject(req, "", 1, 3); // To list all items in req object by 3 levels
// Use this as AFutils.reportObject(req, "headers", 1, 10); // To find "headers" item and then list by 10 levels
// yes, I'm OLD School! I like to see the scope start AND end!!! :-P
exports.reportObject = function(obj, key, level, deep)
{
if (!obj)
{
return;
}
var nextLevel = level + 1;
var keys, typer, prop;
if(key != "")
{ // requested field
keys = key.split(']').join('').split('[');
}
else
{ // do for all
keys = Object.keys(obj);
}
var len = keys.length;
var add = "";
for(var j = 1; j < level; j++)
{
// I would normally do {add = add.substr(0, level)} of a precreated multi-tab [add] string here, but Sublime keeps replacing with spaces, even with the ["translate_tabs_to_spaces": false] setting!!! (angry)
add += "\t";
}
for (var i = 0; i < len; i++)
{
prop = obj[keys[i]];
if(!prop)
{
// Don't show / waste of space in console window...
//console.log(add + level + ": UNDEFINED [" + keys[i] + "]");
}
else
{
typer = typeof(prop);
if(typer == "function")
{
// Don't bother showing fundtion code...
console.log(add + level + ": [" + keys[i] + "] = {" + typer + "}");
}
else
if(typer == "object")
{
console.log(add + level + ": [" + keys[i] + "] = {" + typer + "}");
if(nextLevel <= deep)
{
// drop the key search mechanism if first level item has been found...
this.reportObject(prop, "", nextLevel, deep); // Recurse into
}
}
else
{
// Basic report
console.log(add + level + ": [" + keys[i] + "] = {" + typer + "} = " + prop + ".");
}
}
}
return ;
};
//console.log("END: AFutils");
Source: Stackoverflow.com