I am puzzled as to why I can not store the word length in a javascript array.
I have tried
var i = [];
i["length"] = "ABC";
i["len"+"gth"] = "ABC";
but both aren't accepted in javascript. Can anyone explain it, and is there a way that I can store the word length in an array as above.
Since some asked for more detail. I am creating a list of words that I need to do a lookup at and find the value to display to the user. My list contains for example:
localVars.FunctionDic = [];
localVars.FunctionDic["lastindexof"] = "LastIndexOf(text, textToLocate)";
localVars.FunctionDic["specificindexof"] = "SpecificIndexOf(text, textToLocate, indexNumber)";
localVars.FunctionDic["empty"] = "Empty(text)";
localVars.FunctionDic["length"] = "Length(text)";
everything works except for the "length"
and I am using an array since I need to test if the word a user search for is in my array, and if it is display the value, if it is not, show nothing
It does not work because you are trying to write a string to a property that only allows a number.
From MDN: The length property of an object which is an instance of type Array sets or returns the number of elements in that array. The value is an unsigned, 32-bit integer that is always numerically greater than the highest index in the array.
With the limited details in your question it is hard to tell what you are actually trying to accomplish. It seems like you want to use an array like an object. If that is the case, use an object.
var i = {};
i["length"] = "ABC";
Based on the expected output, I believe you should be using an object not an array.
const FunctionDic = {
lastindexof: "LastIndexOf(text, textToLocate)",
specificindexof: "SpecificIndexOf(text, textToLocate, indexNumber)",
empty: "Empty(text)",
length: "Length(text)",
};
console.log(FunctionDic["lastindexof"]);
console.log(FunctionDic["specificindexof"]);
console.log(FunctionDic["empty"]);
console.log(FunctionDic["length"]);
To store the word length in an array you can do:
var i = ["length"]
If you want to store the length of a word in an array you can do:
var lengthOfHello = "hello".length
var i = [lengthOfHello]
var i = ["ABC"];
console.log(new Array(i[0].length).length);
Related
I have a string which is name=noazet difficulty=easy and I want to produce the two words noazet and easy. How can I do this in JavaScript?
I tried var s = word.split("=");
but it doesn't give me what I want .
In this case, you can do it with that split:
var s = "name=noazet difficulty=easy";
var arr = s.split('=');
var name = arr[0]; //= "name"
var easy = arr[2]; //= "easy"
here, s.split('=') returns an array:
["name","noazet difficulty","easy"]
you can try following code:
word.split(' ').map(function(part){return part.split('=')[1];});
it will return an array of two elements, first of which is name ("noazet") and second is difficulty ("easy"):
["noazet", "easy"]
word.split("=") will give you an array of strings which are created by cutting the input along the "=" character, in your case:
results = [name,noazet,difficulty,easy]
if you want to access noazet and easy, these are indices 1 and 3, ie.
results[1] //which is "noazet"
(EDIT: if you have a space in your input, as it just appeared in your edit, then you need to split by an empty string first - " ")
Based on your data structure, I'd expect the desired data to be always available in the odd numbered indices - but first of all I'd advise using a different data representation. Where is this string word coming from, user input?
Just as an aside, a better idea than making an array out of your input might be to map it into an object. For example:
var s = "name=noazet difficulty=easy";
var obj = s.split(" ").reduce(function(c,n) {
var a = n.split("=");
c[a[0]] = a[1];
return c;
}, {});
This will give you an object that looks like this:
{
name: "noazert",
difficulty: "easy"
}
Which makes getting the right values really easy:
var difficulty = obj.difficulty; // or obj["difficulty"];
And this is more robust since you don't need to hard code array indexes or worry about what happens if you set an input string where the keys are reversed, for example:
var s = "difficulty=easy name=noazet";
Will produce an equivalent object, but would break your code if you hard coded array indexes.
You may be able to get away with splitting it twice: first on spaces, then on equals signs. This would be one way to do that:
function parsePairs(s) {
return s.split(' ').reduce(
function (dict, pair) {
var parts = pair.split('=');
dict[parts[0]] = parts.slice(1).join('=');
return dict;
},
{}
);
}
This gets you an object with keys equal to the first part of each pair (before the =), and values equal to the second part of each pair (after the =). If a string has multiple equal signs, only the first one is used to obtain the key; the rest become part of the value. For your example, it returns {"name":"noazet", "difficulty":"hard"}. From there, getting the values is easy.
The magic happens in the Array.prototype.reduce callback. We've used String.prototype.split to get each name=value pair already, so we split that on equal signs. The first string from the split becomes the key, and then we join the rest of the parts with an = sign. That way, everything after the first = gets included in the value; if we didn't do that, then an = in the value would get cut off, as would everything after it.
Depending on the browsers you need to support, you may have to polyfill Array.prototype.reduce, but polyfills for that are everywhere.
im trying to store some object element from one array to another so lets say i have this array of objects
var Array = [{name:'Fadi'},{name:'Joseph'},{name:'Salim'},{name:'Tony'}];
and i want to store the first two object in this array to another array so it would like be
var SubArray =[{name:'Fadi'},{name:'Joseph'}];
thanks in advance for any help.
You can use slice method for this:
var SubArray = Array.slice(0,2);
Please note that Array is reserved JS global object. You need to use different name for that variable. So your code should be for example:
var MyArray = [{name:'Fadi'},{name:'Joseph'},{name:'Salim'},{name:'Tony'}];
var SubArray = MyArray.slice(0,2);
If you need conditional logic you want Array.filter(). If you know you always want the items by index then use slice as in antyrat's answer.
var originalArray = [{name:'Fadi'},{name:'Joseph'},{name:'Salim'},{name:'Tony'}];
var subArray = originalArray.filter(function(obj,index) {
return obj.name=="Fadi" || obj.name=="Joseph";
})
I'm trying to create a 2 dimensional string array in javascript that will allow an unlimited length in the first dimension, but a limited or unlimited length in the second dimension. The first dimension will need to be able to take in a string as a way to store and access the array. So let's say you have type and fieldNumber as the 2 dimensions. I would like to be able to store the array as such:
array[type][fieldNum] = value;
And type has to be able to be String.
I've been searching around, but all I found were either create a 1 dimension String array, create a 2 dimension array with row and col limits, and I couldn't find anywhere that allows me to do what I specified. Can anyone help out?
You can't declare a multi dimensional array in javascript. But you can put an array in an array.
var myArray = [];
myArray.push([]);
myArray[0][1] = 'test';
So in your case, you must handle when you try to reach an empty index in your array (and fill this index with an empty array).
I would like to be able to store the array as such:
array[type][fieldNum] = value;
What about this ? (using object)
var a ={};
a[type]= {};
a[type][fieldname]=someValue;
so :
var a ={};
a["john"]={};
a["john"]["age"]=40;
a["paul"]={};
a["paul"]["age"]=70;
this is no array, its an object when using strings as identifiers.
Objects/Arrays in Javascript are of unlimited length by default.
object = {};
//define 2nd dimension
object["name"] = {};
//enter stuff
object["name"]["id"] = 5;
This is the array:
{"C8_235550":
{"listing":"aut,C8_235550_220144650654"},
"C8_231252":
{"listing":"aut,C8_231252_220144650654"}}
It was fetched with a GET request from a Firebase database using Google Apps Script.
var optList = {"method" : "get"};
var rsltList = UrlFetchApp.fetch("https://dbName.firebaseio.com/KeyName/.json", optList );
var varUrList = rsltList.getContentText();
Notice the .getContentText() method.
I'm assuming that the array is now just a string of characters? I don't know.
When I loop over the returned data, every single character is getting pushed, and the JavaScript code will not find key/value pairs.
This is the FOR LOOP:
dataObj = The Array Shown At Top of Post;
var val = dataObj;
var out = [];
var someObject = val[0];
for (var i in someObject) {
if (someObject.hasOwnProperty(i)) {
out.push(someObject[i]);
};
};
The output from the for loop looks like this:
{,",C,8,_,2,3,5,5,5,0,",:,{,",l,i,s,t,i,n,g,",:,",a,u,t,,,C,8,_,2,3,5,5,5,0,_,2,2,0,1,4,4,6,5,0,6,5,4,",},,,",C,8,_,2,3,1,2,5,2,",:,{,",l,i,s,t,i,n,g,",:,",a,u,t,,,C,8,_,2,3,1,2,5,2,_,2,2,0,1,4,4,6,5,0,6,5,4,",},}
I'm wondering if the array got converted to a string, and is no longer recognized as an array, but just a string of characters. But I don't know enough about this to know what is going on. How do I get the value out for the key named listing?
Is this now just a string rather than an array? Do I need to convert it back to something else? JSON? I've tried using different JavaScript array methods on the array, and nothing seems to return what it should if the data was an array.
here is a way to get the elements out of your json string
as stated in the other answers, you should make it an obect again and get its keys and values.
function demo(){
var string='{"C8_235550":{"listing":"aut,C8_235550_220144650654"},"C8_231252":{"listing":"aut,C8_231252_220144650654"}}';
var ob = JSON.parse(string);
for(var propertyName in ob) {
Logger.log('first level key = '+propertyName);
Logger.log('fisrt level values = '+JSON.stringify(ob[propertyName]));
for(var subPropertyName in ob[propertyName]){
Logger.log('second level values = '+ob[propertyName][subPropertyName]);
}
}
}
What you have is an object, not an array. What you need to do is, use the
Object.keys()
method and obtain a list of keys which is the field names in that object. Then you could use a simple for loop to iterate over the keys and do whatever you need to do.
Can anyone explain why the second alert says 0 ?
var pollData = new Array();
pollData['pollType'] = 2;
alert(pollData['pollType']); // This prints 2
alert(pollData.length); // This prints 0 ??
The length of the array is only changed when you add numeric indexes. For example,
pollData["randomString"] = 23;
has no effect on length, but
var pollData = [];
pollData["45"] = "Hello";
pollData.length; // 46
changes the length to 46. Note that it doesn't matter if the key was a number or a string, as long as it is a numeric integer.
Besides, you are not supposed to use arrays in this manner. Consider it more of a side effect, since arrays are objects too, and in JavaScript any object can hold arbitrary keys as strings.
Because you haven't put anything into the array yet. You've only been assigning to a dynamically-created pollType attribute on the array object.
If you use numeric indices, then the array automagically takes care of length. For example:
var arr = [ ]; // same as new Array()
arr[2] = 'Banana!';
alert(arr.length); // prints 3 (indexes 0 through 2 were created)
The length property takes into consideration only those members of the array which names are indexes (like '1', '2', '3', ... ).
Arrays in JavaScript have numeric indexes only.
Use an object, which is essentially what you are doing above, setting properties on that array object.
array.length returns how many values are stored in the array. The first alert is returning the value of the position 'pollType'.
The reference guide I always use when needing help with javascript arrays is this page http://www.hunlock.com/blogs/Mastering_Javascript_Arrays
I'd also read what it says under the heading Javascript Does Not Support Associative Arrays, as you may run into problems with this also.
var pollData = Array();
function test() {
pollData[0] = 2
alert(pollData[0]);
alert(pollData.length);
}
//[x] is the array position; hence ['polltype'] is causing issues