Develop Reference

Checking for an item in an array

I'm having trouble finding the right way to find if an item from a for loop is in an array. Let's say I have a for loop that is iterating through some results. If they are in an array:
ctids = [];
continue to the next step in the for loop, but if not, push them to the array and do something else. What is the correct syntax for this?
for (var i=0;i<results.features.length;i++){
ACS_BG = results.features[i].attributes.BLKGRPCE;
ACS_ST = results.features[i].attributes.STATEFP;
ACS_CNTY = results.features[i].attributes.COUNTYFP;
ACS_TRCT = results.features[i].attributes.TRACTCE;
if ACS_TRCT exists in ctids { //This is where I am having trouble.
continue; //skip the rest of the if statement
} else {
ctids.push(ACS_TRCT);
// do something else;
};
};

Can you please try this code
var ctids = []
for (var i=0;i<results.features.length;i++){
ACS_BG = results.features[i].attributes.BLKGRPCE;
ACS_ST = results.features[i].attributes.STATEFP;
ACS_CNTY = results.features[i].attributes.COUNTYFP;
ACS_TRCT = results.features[i].attributes.TRACTCE;
if(!ctids.includes(ACS_TRCT))
{
ctids.push(ACS_TRCT);
}
};

You can use includes to check if the elment exist in array and if not push the element into it.
if (ctids.includes(ACS_TRCT)){
continue;
}else{
ctids.push(ACS_TRCT)
}

I'd do:
for (var i = 0; i < results.features.length; i++) {
const ACS_BG = results.features[i].attributes.BLKGRPCE;
const ACS_ST = results.features[i].attributes.STATEFP;
const ACS_CNTY = results.features[i].attributes.COUNTYFP;
const ACS_TRCT = results.features[i].attributes.TRACTCE;
// push ACS_TRCT, ACS_ST, ACS_TRCT, ACS_CNTY to resulting
// array ctids if they don't present using `.includes` method.
if (!ctids.includes(ACS_TRCT)) ctids.push(ACS_TRCT);
if (!ctids.includes(ACS_ST)) ctids.push(ACS_ST);
if (!ctids.includes(ACS_CNTY)) ctids.push(ACS_CNTY);
if (!ctids.includes(ACS_TRCT)) ctids.push(ACS_TRCT);
}

You can use .find to check if the item is already present in the array ( will only work for primitive types )
var found = ctids.find(function(value) {
return ACS_TRCT === value;
});
if(!found) {
ctids.push(ACS_TRCT);
}

How to loop through all the array of objects?

I have an Array of Object to be used to draw a HTML Table:
Array(5)
0: Object
id: 4
name: Sand Jane
address: Green Sand Street
...
...
...
1: Object
2: Object
...
...
...
I am able to do a single name column defined search with
const temp = this.temp.filter(function (d) {
return d.name.toLowerCase().indexOf(val) !== -1 || !val;
});
temp will contain the filtered data of this.temp
Now I just can't figure out how to loop through all object keys (id,name,address...) so that I can do a global column search in the Table.
UPDATE: I have tried this,
const temp = [];
this.temp.forEach(element => {
for (let key in element) {
if (element.hasOwnProperty(key)) {
let v = element[key];
if (v.toString().toLowerCase().indexOf(val) !== -1 || !val) {
temp.push(element);
}
}
}
});
It works but with performance issues.
RESOLVED: Putting a break after temp.push fixed this issue. Thank you all for the guidelines and references.

temp.forEach(item=>{
for(let key in item) {
//item[key] gives you access to each value
}
})

You can iterate through for loops or even you can usefor loop inside a for loop. Either way it's self explanatory.
var dictionary = {
"employee1":[
{"id":"0","name":"Google"},
{"id":"1","name":"eBay"}
],
"employee2": [
{"id":"2","name":"Yahoo"},
{"id":"3","name":"Facebook"}
]
};
var employee1 = dictionary.employee1;
var employee2 = dictionary.employee2;
for ( var i in employee1) {
var id = employee1[i].id;
var name = employee1[i].name;
console.log(id);
console.log(name);
}
for ( var i in employee2) {
var id = employee2[i].id;
var name = employee2[i].name;
console.log(id);
console.log(name);
}

Accessing dynamic values from JSON object in javascript

this is my json object. i need to get only all the values of packageName and assign it to an array. can any body help me with that. i can not go for using indexes since this is dynamic object.
thanks in advance.
var data = [
{
"packageName":"string",
"packageValue":"string"
},
{
"packageName":"string",
"packageValue":"string"
}
]

Use javascript map function
var packageNames = data.map(function(obj){
return obj.packageName;
})
var data=[
{
"packageName":"string1",
"packageValue":"string"
},
{
"packageName":"string2",
"packageValue":"string"
}
]
var packageNames = data.map(function(obj){
return obj.packageName;
})
console.log(packageNames)

You can use filter function and add to array only when this key exists.
var arr = [];
data.filter(getValue)
function getValue(data){
if(data[packageName]){
arr.push(data[packageName])
}
}

You can add an if statement to check the key and then push it to an array.
for(var i = 0; i< data.length; i++){
for (var property in data[i]) {
if (data[i].hasOwnProperty(property)) {
console.log(property);
console.log(data[i][property]);
}
}
}

Javascript : Select Element in URL with multiple instance of the same element

i need to retrieve a value from an URL in JS, my problem is in this url, the element is repeated at least twice with different value. What i need is the last one.
Example :
http://randomsite.com/index.php?element1=random1&element2=random2&element1=random3
and what i want is "random3" and NOT "random1"
I've tried url.match(/.(\&|\?)element1=(.?)\&/)[2];
But it always gives me the first one :(
I don't have the possibility to change how the url is written as this is for a browser extension.

var ws = "http://randomsite.com/index.php?element1=random1&element2=random2&element1=random3",
input = ws.split("?")[1].split("&"),
dataset = {},
val_to_find = "element1";
for ( var item in input){
var d = input[item].split("=");
if (!dataset[d[0]]){ dataset[d[0]] = new Array(); dataset[d[0]].push(d[1]); }
else{
dataset[d[0]].push(d[1]);
}
}
console.log("item: ", dataset[val_to_find][dataset[val_to_find].length -1]);
return dataset[val_to_find][dataset[val_to_find].length -1];
http://jsfiddle.net/wMuHW/

Take the minimum value (other than -1) from urlString.lastIndexOf("&element1=") and urlString.lastIndexOf("?element1="), then use urlString.substring.
Or alternately, split the string up:
var parts = urlString.split(/[?&]/);
...which will give you:
[
"http://randomsite.com/index.php",
"element1=random1",
"element2=random2",
"element1=random3"
]
...then start looping from the end of the array finding the first entry that starts with element= and grabbing the bit after the = (again with substring).

You could;
for (var result, match, re = /[&?]element1=(.+?)(\&|$)/g; match = re.exec(url);) {
result = match[1];
}
alert(result);

Id try keeping a nested array of duplicate elements
function parseQueryString() {
var elements = {},
query = window.location.search.substring(1),
vars = query.split('&');
for (var i = 0; i < vars.length; i++) {
var pair = vars[i].split('='),
key = decodeURIComponent(pair[0]),
value = decodeURIComponent(pair[1]);
if (elements.hasOwnProperty(key)) {
elements[key].push(value);
}
else {
elements[key] = [value];
}
}
}
Used on: www.example.com?element1=hello&element2=test&element1=more
Would give you the object:
{
element1: [
"hello",
"more"
],
element2:[
"test"
]
}

Get value from json object without count the array number

This is my json object i want to get alert it without the array order like[0], [1].
var jsononj = {
"objnew" :
[{testarry: "thi is my demo text" },
{testarry2: "thi is my demo text2" }
] };
}
var newtest = jsononj.objnew[0].testarry;
alert(newtest);
i want to alert without [0]. how to i achieve this

I think this is what you're looking for:
var i;
for (i = 0; i < jsonobj.objnew.length; i++) {
if (jsonobj.objnew[i].testarry) {
alert(jsonobj.objnew[i].testarry);
}
}

This is just stupid but I removed the [0]
var jsononj = {
"objnew" : [
{testarry: "thi is my demo text" },
{testarry2: "thi is my demo text2" }
]
};
var a = jsononj.objnew.shift();
alert(a.testarry);
jsononj.objnew.unshift(a);

That's not JSON, that's a Javascript object. JSON is a text format for representing data.
If you want to look for an object with a specific property, loop through the objects in the array and check for it:
var newtest = null;
for (var i = 0; i < jsononj.objnew.length; i++) {
var obj = jsononj.objnew[i];
if (obj.hasOwnProperty('testarry') {
newtest = obj.testarry;
break;
}
}
if (newtest != null) {
// found one
}

doing a var firstOne = jsononj.objnew[0];
but if you simply don't like the [0] through your lines, extend the Array prototype
Array.prototype.first = function () {
return this[0];
};
var newtest = jsononj.objnew.first().testarry;
alert(newtest);
more info at First element in array - jQuery