From an array of objects, extract value of a property as array

Source: https://stackoverflow.com/questions/19590865/from-an-array-of-objects-extract-value-of-a-property-as-array

Here is a shorter way of achieving it:

let result = objArray.map(a => a.foo);

or

let result = objArray.map(({ foo }) => foo)

Two ways to empty an array

Source: https://www.jstips.co/en/javascript/two-ways-to-empty-an-array/

var foo = [1,2,3];
var bar = [1,2,3];
var foo2 = foo;
var bar2 = bar;
foo = [];
bar.length = 0;
console.log(foo, bar, foo2, bar2);

// [] [] [1, 2, 3] []

• list = [] assigns a reference to a new array to a variable, while any other references are unaffected. which means that references to the contents of the previous array are still kept in memory, leading to memory leaks.
• list.length = 0 deletes everything in the array, which does hit other references.

In other words, if you have two references to the same array (a = [1,2,3]; a2 = a;), and you delete the array’s contents using list.length = 0, both references (a and a2) will now point to the same empty array. (So don’t use this technique if you don’t want a2 to hold an empty array!)

Think about what this will output:

Remove last item from array

Source: https://stackoverflow.com/questions/19544452/remove-last-item-from-array

Use splice(index,howmany)

arr.splice(-1,1)

How to extend an existing JavaScript array with another array, without creating a new array

Source: https://stackoverflow.com/questions/1374126/how-to-extend-an-existing-javascript-array-with-another-array-without-creating

The .push method can take multiple arguments. You can use the spread operator to pass all the elements of the second array as arguments to .push:

>>> a.push(...b)

If your browser does not support ECMAScript 6, you can use .apply instead:

>>> a.push.apply(a, b)

Or perhaps, if you think it's clearer:

>>> Array.prototype.push.apply(a,b)

Please note that all these solutions will fail with a stack overflow error if array b is too long (trouble starts at about 100,000 elements, depending on the browser). If you cannot guarantee that b is short enough, you should use a standard loop-based technique described in the other answer.

Angular 2 TypeScript how to find element in Array

Source: https://stackoverflow.com/questions/37969984/angular-2-typescript-how-to-find-element-in-array

You need to use method Array.filter:

this.persons =  this.personService.getPersons().filter(x => x.id == this.personId)[0];

or Array.find

this.persons =  this.personService.getPersons().find(x => x.id == this.personId);

Iterate over array of objects in Typescript

Source: https://stackoverflow.com/questions/46213989/iterate-over-array-of-objects-in-typescript

You can use the built-in forEach function for arrays.

Like this:

//this sets all product descriptions to a max length of 10 characters
data.products.forEach( (element) => {
    element.product_desc = element.product_desc.substring(0,10);
});

Your version wasn't wrong though. It should look more like this:

for(let i=0; i<data.products.length; i++){
    console.log(data.products[i].product_desc); //use i instead of 0
}