Develop Reference

Using already created functions inside a new Javascript function

I'm beginner, so this question might be silly.
I had to do 4 Javascript Function, I will put them below
function Square(a) {
b=a*a;
return b;
}
//2.Functia Half//
function Half(a) {
b=a/2;
return b;
}
//3.Functia Percent//
function Percent(a,b) {
procent=a/b*100;
return procent + "%";
}
//4.Functia Area//
function Area(a) {
pi=3.14;
circlearea=a*a*pi;
final=circlearea.toFixed(0);
return final;
}
Now i have to create the last function, which does:
Applies Half function on the parameter I've given to the new function(a), stores is in a new variable(result), result becomes parameter for the function square, the result will be stored again in a new variable(resultSquare), resultSquare will be used in Area function and stored in a new variable(resultArea). In the end, I need percent function, to find out the percent of resultArea from resultSquare. I tried like this, but no luck:
function new function{
result=Half(a);
return result;
resultSquare=Square(result);
return resultSquare;
}
It just returns result variable and does nothing else. Can you help? Thank you in advance.

You can't return something twice. Once you return something, it breaks out of the function. Remove the first return result; statement and it should work.
Also why are you doing
function new function { }
The proper syntax is
function [Function Name](parameters) { }

The result exits the function - so anything after a return statement will not be run. You need to return the last item:
function newFunction(a) {
var result = Half(a);
var resultSquare = Square(a);
var resultArea = Area(a);
return Percent(resultSquare, resultArea);
}

Data structure adding and removing items using constructor functions

Its the beginning of a data structure exercise and I am trying to write an add and remove function -its should be so simple and I don't get why its wrong?! Also the way to do it 8using a constructor function, prototype etc. must stay the way it is)
Any help much appreciated!
function Thestack () {
this.array=[];
}
Thestack.prototype.plus = function (i) {
this.array.push(i);
return this; // cannot be edited
};
Thestack.prototype.minus = function () {
this.array.pop();
};
var smallstack = new Thetack();
smallstack.plus(something); //followed by
smallstack.minus();
should return: something

your minus function does not have a return statement, so it just returns undefined by default
You could as in the add function return this so you can continue chaining of methods, return the element removed or return the length of the remaing array
// return this for chaining
Thestack.prototype.minus = function () {
this.data.pop();
return this;
};
// return the removed item
Thestack.prototype.minus = function () {
//edits the data array in place and returns the last element
return this.data.pop();
};
// return the length of the remaining array
Thestack.prototype.minus = function () {
this.data.pop();
return this.data.length;
};

higher order functions using arrays in javascript

I am trying to create a higher order function in javascript someMathArray(x) { } that returns a function and takes another single argument. I want the function to take an original array, say [1,2,3,4] then apply another function for example, named mult2(a) { return a*2 }(however, I want this to work for any function I pass in. I don't want mult2(a) to be hard coded into the function) and then return an array containing [2,4,6,8]

Something like this?
function someMathArray(array) {
return function(fun) {
return array.map(fun);
};
}
var fun = someMathArray([1,2,3,4,5]);
var output = fun(function(a) { return a*2; });
document.getElementById('output').innerHTML = JSON.stringify(output);
<div id="output"></div>
or
function someMathArray(array) {
return array.map.bind(array);
}
var fun = someMathArray([1,2,3,4,5]);
var output = fun(function(a) { return a*2; });
document.getElementById('output').innerHTML = JSON.stringify(output);
<div id="output"></div>

Javascript function returning undefined for template helper

Creating a template helper to return a variable to be displayed in the DOM, and my function is returning undefined and thus is not affecting the DOM. Not exactly sure why, though I feel as if it is a binding issue. Here's the code:
supportNumber: function(){
var jobSupportNumber = state.user.jobs.each(function(job){
console.log(jobOrder.get("jobId"));
console.log("test");
console.log(job.get("id"));
if(jobOrder.get("jobId") == job.get("id")){
var jobNumber = job.get("supportNumber");
console.log(jobNumber);
return jobNumber;
}
else{
console.log("this fired");
}
});
console.log(jobSupportNumber);
return jobSupportNumber;
}
I'm console logging alot to make sure values are being returned, and something is being returned all the way up until the final return statement, which returns jobSupportNumber as undefined. What am I doing wrong to have it return always as undefined?

.each() doesn't return the value of any of the function it's wrapping. The inner function results are only used to control the .each() loop.
Try this:
supportNumber: function(){
var jobSupportNumber = null;
state.user.jobs.each(function(job){
if(jobOrder.get("jobId") == job.get("id")){
jobSupportNumber = job.get("supportNumber");
return false; // tell .each() to quit looping
}
});
return jobSupportNumber;
}

By the code you have there, state.user.jobs.each() is not going to return jobNumber. That return applies to your anonymous function. (where you have function(job).
To get that value, you want something more like this:
supportNumber: function(){
var jobSupportNumber;
state.user.jobs.each(function(job){
console.log(jobOrder.get("jobId"));
console.log("test");
console.log(job.get("id"));
if(jobOrder.get("jobId") == job.get("id")){
var jobNumber = job.get("supportNumber");
console.log(jobNumber);
/* Set the value and just plain return, instead */
jobSupportNumber = jobNumber;
return;
}
else{
console.log("this fired");
}
});
console.log(jobSupportNumber);
return jobSupportNumber;
}

Angularjs filter always returns true

I've made filter for ng-repaet that looks like this:
$scope.filterRoutine = function(col) {
return _.isEqual(col.Routine.IsIndoor, true);
}
It works fine (isEqual returns true or false).
But this doesn't work, and I don't know why is that (when I say it doesn't work, I don't get any errors, but view doesn't change)
$scope.filterRoutine = function(col) {
return _.forEach(tempData, function (temp) {
if (_.find(col.Exercises, { Exercise: temp })) {
return true;
} else {
return false;
}
});
}
What I do here (or rather what I want to do) is this: I have tempData collection, if my col.Exercises has at least one item from tempData it should be showed in the view.
But for some reason all items are showed in the view i.e. nothing has been filtered.
My guess is that this because this function always returns true (because always at least one col.Exercises should contain item from tempData).
How can I fix this i.e. hide all cols which don't contain any items from tempData ?

Returning from _.forEach does not do what you expect it to do.
You'll need to do something like this:
$scope.filterRoutine = function(col) {
var x = false;
_.forEach(tempData, function (temp) {
if (_.find(col.Exercises, { Exercise: temp })) {
x = true;
}
});
return x
}
Also, "Callbacks may exit iteration early by explicitly returning false.", meaning your return false was stoping iteration after the first time _.find returned false.