Javascript:
This is my example code below. I use prompt() variables to create string values for each loop.
var team = new Object;
team["fwd"] = "forwards";
for (i=1; i <2+1; i++){
var fwdName = prompt("enter player name");
team["fwd"]["p" + i] = fwdName;
}
It is my understanding with the above that in each loop, I get user input to read in a value for each new property (that is created by ["p"+i]) to be set to. The fwdName variable is overwritten with each loop.
I use the following to check that I actually put in values that can be used;
console.log(team.fwd.p1);
console.log(team.fwd.p2);
and I get undefined as output for each statement.
i belive the fwd property of your main object should be an object not a string.
team["fwd"] = {};
Related
I tried using the join() function in my array and tried to document.write it but
the console says"birth.join() is not a function "
birthyear=[];
for(i=1800;i<2018;i++){
birthyear+=i
}
birth=birthyear.join();
document.write(birth);
Array.prototype.join() works on array and to insert an element to array you should call .push() instead of +=, read more about += here.
Always use var before declaring variables, or you end up declaring global variables.
var birthyear = [];
for (i = 1800; i < 2018; i++) {
birthyear.push(i);
}
var birth = birthyear.join(", ");
document.write(birth);
I your code your not appending data to array you are adding data to array variable which is wrong
1st Way
birthyear=[];
for(i=1800;i<2018;i++)
{
birthyear.push(i);
}
birth=birthyear.join();
document.write(birth);
2nd Way
birthyear=[];
k=0;
for(i=1800;i<2018;i++){
birthyear[k++]=i;
}
birth=birthyear.join();
document.write(birth);
You can't apply .push() to a primitive type but to an array type (Object type).
You declared var birthyear = []; as an array but in the body of your loop you used it as a primitive: birthyear+=i;.
Here's a revision:
var birthyear=[];
for(let i=1800;i<2018;i++){
birthyear[i]=i;
// careful here: birthyear[i] += i; won't work
// since birthyear[i] is NaN
}
var birth = birthyear.join("\n");
document.write(birth);
Happy coding! ^_^
I am trying to create a array with multiple fields in it.
For Example:
var person1 = {firstname:"Bob", lastname:"Smith", middlename:"happy"};
The problem I have is that I have 5000 variables I want to create so it would become:
var person1 = {firstname:"Bob", lastname:"Smith", middlename:"happy"};
var person2 = {firstname:"John", lastname:"Jones", middlename:"Long"};
..
var person5000 = {firstname:"Jim", lastname:"Cook", middlename:"Shorty"};
I think it would be silly to have 5000 lines of code to declare the variables.
So I want to be able to declare the variables on page load and then later assign the values to each.
I was trying to do this using the following code but I am guessing I am doing something wrong.
(I am loading some dummy data into the variables for testing)
<!DOCTYPE html>
<html>
<body>
<script>
var person = new Array (firstName:"", lastName:"", middleName:"");
for (var i = 0; i < 5000; ++i) {
person[i] = {firstName:"First"+i, lastName:"Last"+i, middlename:"Middle"+i};
}
alert(person1["firstName"]); // should alert First1
alert(person6["lastname"]); // should alert Last6
</script>
</body>
</html>
I was hoping to later in my code set the value using:
(I am pretty sure this code should work, but can't test it since I can't declare the variables correctly)
person1[firstname] = "Terry"; // should replace First1 with Terry
And then to receive a value using:
alert(person1[firstname]); // should alert Terry since it was changed
Anyone know what is wrong with my code since it's not returning the value ?
I am guessing I am declaring the variables wrong? If so how should I declare them ?
You appear to be confused about the difference between arrays and objects in Javascript. Arrays have numeric indexes, objects have named properties. So the initialization
new Array(firstName:"", lastName:"", middleName:"");
makes no sense. Not to mention, it's not valid Javascript syntax; property: value pairs can only be used in object literals, not in argument lists. If you use new Array(...), the argument should either be a single number, which is the size of the array to allocate, or a list of initial array element (with no property: prefixes. But the preferred way to create a new array is simply with the [] literal for an empty array; it will grow as necessary when you assign to it.
When you create an array, you don't get separate variables for each element. You access them using array[n] notation.
// Create an empty array
var person = [];
// Fill up the array
for (var i = 0; i < 5000; ++i) {
person[i] = {firstName:"First"+i, lastName:"Last"+i, middlename:"Middle"+i};
}
// Access elements
alert(person[1].firstName);
alert(person[6].middleName);
// Change elements
person[1].firstName = "Terry";
I believe this should work as you intended:
var person = new Array();
for (var i = 0; i < 5000; ++i) {
person[i] = {firstName:"First"+i, lastName:"Last"+i, middleName:"Middle"+i};
}
alert(person[1]["firstName"]);
alert(person[6]["lastName"]);
As pointed out by others, the person array is filled with objects, not arrays. You can use either property or associative array syntax with them.
var formRules = $(this).data('rules');
var formValues = $(this).data('values');
if(formRules || formValues){
var rulesArray = formRules.split(',');
var valuesArray = formValues.split(',');
for(var i=0; i < rulesArray.length; i++){
//alert(rulesArray[i]);
$.validationEngine.defaults.rulesArray[i] = valuesArray[i];
}
}
else{
return false;
}
This throws an error like following
Error: TypeError: $.validationEngine.defaults.rulesArray is undefined
Source File: http://localhost:8380/javascript/jquery.validationEngine.js
Line: 2092
I cannot find the problem with this code.Any help is welcome
EDIT:
I am trying to set the global options eg:scroll using the for loop.
The formRules string will have these options comma seperated and the corresponding values in the formValues string.
So i am expecting it to come like $.validationEngine.defaults.scroll = true;
change this line
$.validationEngine.defaults.rulesArray[i] = valuesArray[i];
to this
$.validationEngine.defaults[rulesArray[i]] = valuesArray[i];
rulesArray is not a child of $.validationEngine.defaults. The values stored in your rulesArray are. The syntax in my second code block references everything properly.
This is called Bracket Notation, a way to get an object's property using any sort of valid calculation (like rulesArray[i], or "myStringPropertyName"). see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Member_Operators for other methods.
Is there a way to make the value of a variable the name for another variable? For example, I want the variable name (value_of_i) to be what ever number "i" is during that iteration. The while loop below is not what I'm using it for, it's just to explain what I'm asking.
var i = 1;
while(i<10)
{
var value_of_i = "This loop has ran " + i + "times.";
i++;
}
For the first iteration, "i" is equal to 1 so I would want the variable name to be "1":
var 1 = "This loop has ran " + i + "times.";
And the second interation:
var 2 = "This loop has ran " + i + "times.";
Yes. Using bracket notation (Here is a tutorial in MDN)
Here is a working fiddle
When doing something like containingObject[stringVariable] you are accessing the property in containingObject whose name is the value stored in stringVariable.
// this assumes browser JavaScript where window is the global namespace
// in node.js this would be a little different
var i=0;
while(i<10){
window["counters"+i] = "This is loop has ran " + i + "times.";
i++;
}
console.log(counters3);
If you'd like you can use this instead of window, however this might fail in strict mode.
Here is the main explanation of how bracket notation works from the MDN link above:
Properties of JavaScript objects can also be accessed or set using a bracket notation. Objects are sometimes called associative arrays, since each property is associated with a string value that can be used to access it. So, for example, you could access the properties of the myCar object as follows:
myCar["make"] = "Ford";
myCar["model"] = "Mustang";
myCar["year"] = 1969;
You can also access properties by using a string value that is stored in a variable:
var propertyName = "make";
myCar[propertyName] = "Ford";
propertyName = "model";
myCar[propertyName] = "Mustang";
You can't make a variable name a number, its not a valid name. So var 1="" is invalid.
But to dynamically set the value you can do
var x = "variablenamehere";
window[x] = "variablevaluehere";
Thats the same as
var variablenamehere
except that it will be scoped as a global variable and will be accessible everywhere, rather than being limited to the current function scope.
Why not store your strings in an array that is indexed by i?
That way you can reference them later efficiently and easily;
var loopI = new Array();
for(var i = 0; i < 10; ++i) {
loopI[i] = "This loop has ran " + i + "times.";
}
This works:
var o = {};
var d = "dog";
for (var k = 0; k < 5; k += 1) {
o[d+k] = k*100;
}
console.log(o.dog3); // 300
This comes closer to doing what you want:
var N = {};
var M = {};
var i = 1;
while(i<10)
{
N[i] = "This loop ran " + i + " times.";
// Or, so you can use dot notation later:
M['OO'+i] = "This loop ran " + i + " times.";
// Those are capital O's, not zeros. Numbers won't work.
i++;
}
console.log(N[3]); // This loop ran 3 times.
console.log(M.OO7); // This loop ran 7 times.
The 'OO' notation could cause bewilderment and wasted time for others trying to use your code; but it could also be a source of amusement for them. This reminds me of a chess board after white's first two moves are to bring out a knight and then put it back. The board then seems to show that black moved first, and some people will endlessly insist that the configuration proves there was illegal play unless someone tells them what happened.
This is annoying me.
I'm setting an array in beginning of the doc:
var idPartner;
var myar = new Array();
myar[0] = "http://example.com/"+idPartner;
And I'm getting a number over the address, which is the id of partner. Great. But I'm trying to set it without success:
$.address.change(function(event) {
idPartner = 3;
alert(idPartner);
}
Ok. The alert is giving me the right number, but isn't setting it.
What's wrong?
Changing the value of the variable does not re-set the values within the array. That is just something javascript can't do automatically. You would have to re-generate the array for it to have the new id. Could you add the id to the value where you use the array instead of pre-setting the values in the array containing the id?
Edit: For example, you would do:
var myArray = [];
var myId = 0;
myArray[0] = "http://foo.com/id/";
and when you need to use a value from the array, you would do this:
var theVal = myArray[0] + myId;
Try this:
var myvar = ["http://site.com/"];
$.address.change(function(event) {
myvar[1] = 3;
}
then use myvar.join () where you need the full url.
The problem here is that at the line
myar[0] = "http://site.com/"+idPartner;
..you perform a string concatenation, meaning you copy the resulting string into the array at index position 0.
Hence, when later setting idPartnerit won't have any effect on the previously copied string. To avoid such effect you can either always construct the string again when the idPartnervariable updates or you create an object and you evaluate it when you need it like...
var MyObject = function(){
this.idPartner = 0; //default value
};
MyObject.prototype.getUrl = function(){
return "http://site.com/" + this.idPartner;
};
In this way you could use it like
var myGlblUrlObj = new MyObject();
$.address.change(function(event){
myGlblUrlObj.idPartner = ... /setting it here
});
at some later point you can then always get the correct url using
myGlblUrlObj.getUrl();
Now obviously it depends on the complexity of your situation. Maybe the suggested array solution might work as well, although I prefer having it encapsulated somewhere in an object for better reusability.
myar[0] = "http://site.com/" + idPartner;
After this line, myar[0] = "http://site.com/undefined" and it has nothing to do with the variable idPartner no more.
So, after that changing the value of idPartner will affect the value of myar[0].
You need to change the value of myar[0] itself.