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javascript array confusion between x = [x] && x.push(x) when var x;


By : Asmaa Ramadan
Date : October 16 2020, 08:10 AM
I wish did fix the issue. In case one, the line x.push(x); will throw an error if x is not defined - you can't access properties of an undefined object, of course.
In case two, x is not defined at the point the line x = [x]; is run, but you aren't trying to access any properties of x or anything like that - it's just an undefined value, which is OK. So, the expression [x] results in an array with one item, x (which is undefined), thus [undefined].
code :


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How do I push a group of values to an array with Javascript push()?


By : Reese Montgomery
Date : March 29 2020, 07:55 AM
To fix this issue Can anybody spot the error here? Checkpoint 1 triggers but not checkpoint 2. Can't figure out what's wrong with my statement.
code :
items = {
    itemID: "B17",
    itemPrice: 17,
    itemQty: 1
};
items =[{
    itemID: "B17",
    itemPrice: 17,
    itemQty: 1
}];

Javascript - Why returning array.push(x) from a function doens't push the element x into the array?


By : user3440872
Date : March 29 2020, 07:55 AM
may help you . If you look at the definition of the push method, it returns the length of the array after the push, not the array itself, that is why it is returning 1.

javascript array.push(array.push(x)) weird result


By : Daniela Ganea
Date : March 29 2020, 07:55 AM
I think the issue was by ths following , Array.prototype.push()

Javascript: Customizing an array push based on variable - allowing standard push call for some types


By : Belldozer85
Date : March 29 2020, 07:55 AM
this one helps. I am using the following technique to differentiate between copy-sourcing two different objects. The o2.copy does the deep copy while o3.copy does the shallow copy. , Use .call method for a function object to get default implementation.
code :
var A = [];

A.push = function (o) {
    if (typeof o === "object") {
        A[A.length] = {} 
        for (var key in o) {        
            A[A.length-1][key] = o[key];  
        } 
    } else {
        console.log("Non-object push");
        Array.prototype.push.call(this, o); //<--- How to call the default array push here
    }
}

how to push an item into an array if it is inside a javascript object [state.lastValue.push is not a function]


By : Guillermo Gómez
Date : March 29 2020, 07:55 AM
this will help I'm updating some values as a javascript object inside my reducer in reactjs like below. , Update your state like
code :
state = {
  ...state,
  result:state.result + 400,
  lastval: [...state.lastval, 20]
}
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