Related
I am dealing with a fairly complex object. It contains 2 arrays, which contain 3 arrays each of objects:
I'm trying to delete one of the history: Array[2] if one of the objects in it has username: null.
var resultsArray = result.history;
var arrayCounter = 0;
resultsArray.forEach(function(item) {
item.forEach(function(innerItem) {
if (innerItem.username == null) {
resultsArray.splice(arrayCounter,1);
};
});
arrayCounter++;
});
Looking through answers it's recommended to do something like:
resultsArray.splice(arrayCounter,1);
This isn't working in this situation because more than one of the objects could have username == null and in that case it will delete multiple history objects, not just the one that I want.
How do I remove only the one specific history array index if username == null?
splice is evil. I think using immutable array methods like filter might be easier to reason about:
x.history =
x.history.filter(function (h) {
return !h.some(function (item) {
return item.username === null
})
})
Go through all the histories, and do not include them in the filter if they have a username that is null.
My understanding was that you only want to delete the first outer array that has an inner array that has an object with a null username. Heres one solution closest to your current form:
var resultsArray = result.history;
var arrayCounter = 0;
var foundFirstMatch = false;
resultsArray.forEach(function(item) {
if (!foundFirstMatch) {
item.forEach(function(innerItem) {
if (innerItem.username == null && !foundFirstMatch) {
foundFirstMatch = true;
};
});
arrayCounter++;
}
});
if (foundFirstMatch > 0)
resultsArray.splice(arrayCounter, 1);
Other syntax:
var resultsArray = result.history;
var outerNdx;
var innerNdx;
var foundMatch = false;
for (outerNdx = 0; !foundMatch && outerNdx < resultsArray.length; outerNdx++) {
for (innerNdx = 0; !foundMatch && innerNdx < resultsArray[outerNdx].length; innerNdx++) {
if (resultsArray[outerNdx][innerNdx].username == null) {
foundMatch = true;
}
}
}
if (foundMatch)
resultsArray.splice(outerNdx, 1);
Update - here's how I'd do it now, without lodash:
thing.history.forEach((arr, i) => {
thing.history[i] = arr.filter( (x) => x.username !== null );
});
Previous answer:
I'd use lodash like this:
_.each(thing.history, function(array, k){
thing.history[k] = _.filter(array, function(v){
return v.username !== null;
})
});
Here's a jsfiddle:
https://jsfiddle.net/mckinleymedia/n4sjjkwn/2/
You should write something like this:
var resultsArray = result.history.filter(function(item){
return !item.some(function(inner){ return inner.username==null; });
});
The foreach loop cant break in this way but a regular for loop can. This is working:
result.history.forEach(function(item) {
loop2:
for (var i = 0; i < item.length; i++) {
var innerItem = item[i];
console.log(innerItem);
break loop2;
}
});
Let's say we have the following js array
var ar = [
[2,6,89,45],
[3,566,23,79],
[434,677,9,23]
];
var val = [3,566,23,79];
Is there a js builtin function or jQuery one with which you can search the array ar for val?
Thanks
***UPDATE*************
Taking fusion's response I created this prototype
Array.prototype.containsArray = function(val) {
var hash = {};
for(var i=0; i<this.length; i++) {
hash[this[i]] = i;
}
return hash.hasOwnProperty(val);
}
you could create a hash.
var ar = [
[2,6,89,45],
[3,566,23,79],
[434,677,9,23]
];
var hash = {};
for(var i = 0 ; i < ar.length; i += 1) {
hash[ar[i]] = i;
}
var val = [434,677,9,23];
if(hash.hasOwnProperty(val)) {
document.write(hash[val]);
}
You can also use a trick with JSON serializing. It is short and simple, but kind of hacky.
It works, because "[0,1]" === "[0,1]".
Here is the working demo snippet:
Array.prototype.indexOfForArrays = function(search)
{
var searchJson = JSON.stringify(search); // "[3,566,23,79]"
var arrJson = this.map(JSON.stringify); // ["[2,6,89,45]", "[3,566,23,79]", "[434,677,9,23]"]
return arrJson.indexOf(searchJson);
};
var arr = [
[2,6,89,45],
[3,566,23,79],
[434,677,9,23]
];
document.body.innerText = arr.indexOfForArrays([3,566,23,79]);
function indexOfArray(val, array) {
var hash = {};
for (var i = 0; i < array.length; i++) {
hash[array[i]] = i;
}
return (hash.hasOwnProperty(val)) ? hash[val] : -1;
};
I consider this more useful for than containsArray(). It solves the same problem (using a hash table) but returns the index (rather than only boolean true/false).
Can you try this?
var ar = [
[2,6,89,45],
[3,566,23,79],
[434,677,9,23]
];
var val = [3,566,23,79];
var sval = val.join("");
for(var i in ar)
{
var sar = ar[i].join("");
if (sar==sval)
{
alert("found!");
break;
}
}
Why don't you use javascript array functions?
function filterArrayByValues(array, values) {
return array.filter(function (arrayItem) {
return values.some(function (value) {
return value === arrayItem;
});
});
}
Or if your array is more complicated, and you want compare only one property but as result return whole object:
function filterArrayByValues(array, values, propertyName) {
return array.filter(function (arrayItem) {
return values.some(function (value) {
return value === arrayItem[propertyName];
});
});
}
More about used functions: filter() and some()
You can use Array.prototype.some(), Array.prototype.every() to check each element of each array.
var ar = [
[2, 6, 89, 45],
[3, 566, 23, 79],
[434, 677, 9, 23]
];
var val = [3, 566, 23, 79];
var bool = ar.some(function(arr) {
return arr.every(function(prop, index) {
return val[index] === prop
})
});
console.log(bool);
I guess there is no such JS functionality available. but you can create one
function arrEquals( one, two )
{
if( one.length != two.length )
{
return false;
}
for( i = 0; i < one.length; i++ )
{
if( one[i] != two[i] )
{
return false;
}
}
return true;
}
The problem with this is that of object/array equality in Javascript. Essentially, the problem is that two arrays are not equal, even if they have the same values. You need to loop through the array and compare the members to your search key (val), but you'll need a way of accurately comparing arrays.
The easiest way round this is to use a library that allows array/object comparison. underscore.js has a very attractive method to do this:
for (var i = 0; i < ar.length; i++) {
if (_.isEqual(ar[i], val)) {
// value is present
}
}
If you don't want to use another library (though I would urge you to -- or at least borrow the message from the Underscore source), you could do this with JSON.stringify...
var valJSON = JSON.stringify(val);
for (var i = 0; i < ar.length; i++) {
if (valJSON === JSON.stringify(ar[i]) {
// value is present
}
}
This will almost certainly be significantly slower, however.
You can use toString convertion to compare elements
var ar = [
[2,6,89,45],
[3,566,23,79],
[434,677,9,23]
];
var val = [3,566,23,79];
s = !ar.every(a => (a.toString() != val.toString()));
console.log(s) // true
Use this instead
if (ar.join(".").indexOf(val) > -1) {
return true;
} else {
return false;
}
Use lodash isEqual
const isValIncludedInAr = ar.some(element => isEqual(element, val))
const arrayOne = [2,6,89,45];
const arrayTwo = [3,566,23,79];
const arrayThree = [434,677,9,23];
const data = new Set([arrayOne, arrayTwo, arrayThree]);
// Check array if exist
console.log( data.has(arrayTwo) ); // It will return true.
// If you want to make a set into array it's simple
const arrayData = [...data];
console.log(arrayData); // It will return [[2,6,89,45], [3,566,23,79], [434,677,9,23]]
I would like to find index in array. Positions in array are objects, and I want to filter on their properties. I know which keys I want to filter and their values. Problem is to get index of array which meets the criteria.
For now I made code to filter data and gives me back object data, but not index of array.
var data = [
{
"text":"one","siteid":"1","chid":"default","userid":"8","time":1374156747
},
{
"text":"two","siteid":"1","chid":"default","userid":"7","time":1374156735
}
];
var filterparams = {userid:'7', chid: 'default'};
function getIndexOfArray(thelist, props){
var pnames = _.keys(props)
return _.find(thelist, function(obj){
return _.all(pnames, function(pname){return obj[pname] == props[pname]})
})};
var check = getIndexOfArray(data, filterparams ); // Want to get '2', not key => val
Using Lo-Dash in place of underscore you can do it pretty easily with _.findIndex().
var index = _.findIndex(array, { userid: '7', chid: 'default' })
here is thefiddle hope it helps you
for(var intIndex=0;intIndex < data.length; intIndex++){
eachobj = data[intIndex];
var flag = true;
for (var k in filterparams) {
if (eachobj.hasOwnProperty(k)) {
if(eachobj[k].toString() != filterparams[k].toString()){
flag = false;
}
}
}
if(flag){
alert(intIndex);
}
}
I'm not sure, but I think that this is what you need:
var data = [{
"text":"one","siteid":"1","chid":"default","userid":"8","time":1374156747
}, {
"text":"two","siteid":"1","chid":"default","userid":"7","time":1374156735
}];
var filterparams = {userid:'7', chid: 'default'};
var index = data.indexOf( _.findWhere( data, filterparams ) );
I don't think you need underscore for that just regular ole js - hope this is what you are looking for
var data = [
{
"text":"one","siteid":"1","chid":"default","userid":"8","time":1374156747
},
{
"text":"two","siteid":"1","chid":"default","userid":"7","time":1374156735
}
];
var userid = "userid"
var filterparams = {userid:'7', chid: 'default'};
var index;
for (i=0; i < data.length; i++) {
for (prop in data[i]) {
if ((prop === userid) && (data[i]['userid'] === filterparams.userid)) {
index = i
}
}
}
alert(index);
var arr = [["test","1"],["demo","2"]];
// $.inArray() ???
// .splice() ???
// $.each() ???
$("code").html(JSON.stringify(arr));
If I will find matching array by "test" (unique) keyword , I will remove ["test","1"]
So arr after removed will be [["demo","2"]]
How can I do that ?
Playground : http://jsbin.com/ojoxuy/1/edit
This is what filter is for:
newArr = arr.filter(function(item) { return item[0] != "test" })
if you want to modify an existing array instead of creating a new one, just assign it back:
arr = arr.filter(function(item) { return item[0] != "test" })
Modificator methods like splice make code harder to read and debug.
You could do something like this:
function remove(oldArray, itemName) {
var new_array = [];
for(var i = 0, len = oldArray.length; i < len; i++) {
var arr = oldArray[i];
if (arr[0] != itemName) new_array.push(arr);
}
return new_array;
}
And call it like this:
var arr = [["test","1"],["demo","2"]];
var new_arr = remove(arr,'test');
I'm making assumptions here and not doing any real error checking but you get the idea.
Perhaps something like:
for(var i = 0; i < arr.length; i++) {
if(arr[i][0] == "test") {
arr.splice(i, 1);
break;
}
}
var arr = [["test","1"],["demo","2"]];
function checkArrayElements(a, index, arr) {
if(a[0]=="test"){
delete arr[index];
arr.splice(index,index+1);
}
}
arr.forEach(checkArrayElements);
$("code").html(JSON.stringify(arr));
NOTE: This removes any inner array in arr with the 0 element = "test"
Check this one
function rmEl(a,v)
{
for(var i=0;i<a.length;i++)
{
if(a[i][0]==v)
{
a.splice(i,i+1);
i=-1;
}
$("code").html(JSON.stringify(a));
}
return a;
}
Let's say we have the following js array
var ar = [
[2,6,89,45],
[3,566,23,79],
[434,677,9,23]
];
var val = [3,566,23,79];
Is there a js builtin function or jQuery one with which you can search the array ar for val?
Thanks
***UPDATE*************
Taking fusion's response I created this prototype
Array.prototype.containsArray = function(val) {
var hash = {};
for(var i=0; i<this.length; i++) {
hash[this[i]] = i;
}
return hash.hasOwnProperty(val);
}
you could create a hash.
var ar = [
[2,6,89,45],
[3,566,23,79],
[434,677,9,23]
];
var hash = {};
for(var i = 0 ; i < ar.length; i += 1) {
hash[ar[i]] = i;
}
var val = [434,677,9,23];
if(hash.hasOwnProperty(val)) {
document.write(hash[val]);
}
You can also use a trick with JSON serializing. It is short and simple, but kind of hacky.
It works, because "[0,1]" === "[0,1]".
Here is the working demo snippet:
Array.prototype.indexOfForArrays = function(search)
{
var searchJson = JSON.stringify(search); // "[3,566,23,79]"
var arrJson = this.map(JSON.stringify); // ["[2,6,89,45]", "[3,566,23,79]", "[434,677,9,23]"]
return arrJson.indexOf(searchJson);
};
var arr = [
[2,6,89,45],
[3,566,23,79],
[434,677,9,23]
];
document.body.innerText = arr.indexOfForArrays([3,566,23,79]);
function indexOfArray(val, array) {
var hash = {};
for (var i = 0; i < array.length; i++) {
hash[array[i]] = i;
}
return (hash.hasOwnProperty(val)) ? hash[val] : -1;
};
I consider this more useful for than containsArray(). It solves the same problem (using a hash table) but returns the index (rather than only boolean true/false).
Can you try this?
var ar = [
[2,6,89,45],
[3,566,23,79],
[434,677,9,23]
];
var val = [3,566,23,79];
var sval = val.join("");
for(var i in ar)
{
var sar = ar[i].join("");
if (sar==sval)
{
alert("found!");
break;
}
}
Why don't you use javascript array functions?
function filterArrayByValues(array, values) {
return array.filter(function (arrayItem) {
return values.some(function (value) {
return value === arrayItem;
});
});
}
Or if your array is more complicated, and you want compare only one property but as result return whole object:
function filterArrayByValues(array, values, propertyName) {
return array.filter(function (arrayItem) {
return values.some(function (value) {
return value === arrayItem[propertyName];
});
});
}
More about used functions: filter() and some()
You can use Array.prototype.some(), Array.prototype.every() to check each element of each array.
var ar = [
[2, 6, 89, 45],
[3, 566, 23, 79],
[434, 677, 9, 23]
];
var val = [3, 566, 23, 79];
var bool = ar.some(function(arr) {
return arr.every(function(prop, index) {
return val[index] === prop
})
});
console.log(bool);
I guess there is no such JS functionality available. but you can create one
function arrEquals( one, two )
{
if( one.length != two.length )
{
return false;
}
for( i = 0; i < one.length; i++ )
{
if( one[i] != two[i] )
{
return false;
}
}
return true;
}
The problem with this is that of object/array equality in Javascript. Essentially, the problem is that two arrays are not equal, even if they have the same values. You need to loop through the array and compare the members to your search key (val), but you'll need a way of accurately comparing arrays.
The easiest way round this is to use a library that allows array/object comparison. underscore.js has a very attractive method to do this:
for (var i = 0; i < ar.length; i++) {
if (_.isEqual(ar[i], val)) {
// value is present
}
}
If you don't want to use another library (though I would urge you to -- or at least borrow the message from the Underscore source), you could do this with JSON.stringify...
var valJSON = JSON.stringify(val);
for (var i = 0; i < ar.length; i++) {
if (valJSON === JSON.stringify(ar[i]) {
// value is present
}
}
This will almost certainly be significantly slower, however.
You can use toString convertion to compare elements
var ar = [
[2,6,89,45],
[3,566,23,79],
[434,677,9,23]
];
var val = [3,566,23,79];
s = !ar.every(a => (a.toString() != val.toString()));
console.log(s) // true
Use this instead
if (ar.join(".").indexOf(val) > -1) {
return true;
} else {
return false;
}
Use lodash isEqual
const isValIncludedInAr = ar.some(element => isEqual(element, val))
const arrayOne = [2,6,89,45];
const arrayTwo = [3,566,23,79];
const arrayThree = [434,677,9,23];
const data = new Set([arrayOne, arrayTwo, arrayThree]);
// Check array if exist
console.log( data.has(arrayTwo) ); // It will return true.
// If you want to make a set into array it's simple
const arrayData = [...data];
console.log(arrayData); // It will return [[2,6,89,45], [3,566,23,79], [434,677,9,23]]