It comes ultimately from mathematics: the summation notation traditionally uses i for the first index, j for the second, and so on. Example (from http://en.wikipedia.org/wiki/Summation): It’s also used that way for collections of things, like if you have a bunch of variables x1, x2, … xn, then an arbitrary one will be known as xi. … Read more
VB6/VBA uses deterministic approach to destoying objects. Each object stores number of references to itself. When the number reaches zero, the object is destroyed. Object variables are guaranteed to be cleaned (set to Nothing) when they go out of scope, this decrements the reference counters in their respective objects. No manual action required. There are … Read more
basic usage Use the safe-navigation operator {{category?.name}} then name is only read when category is not null. array This only works for the . (dereference) operator. For an array you can use {{records && records[0]}} See also Angular 2 – Cannot read property ‘0’ of undefined error with context ERROR CONTEXT: [object Object] async pipe … Read more
If you’re coming from C/C++, it might also be helpful to think of it basically like this: // Rust C/C++ a: &T == const T* const a; // can’t mutate either mut a: &T == const T* a; // can’t mutate what is pointed to a: &mut T == T* const a; // can’t mutate … Read more
This is actually possible to do using SASS maps instead of variables. Here is a quick example: Referencing dynamically: $colors: ( blue: #007dc6, blue-hover: #3da1e0 ); @mixin colorSet($colorName) { color: map-get($colors, $colorName); &:hover { color: map-get($colors, #{$colorName}-hover); } } a { @include colorSet(blue); } Outputs as: a { color:#007dc6 } a:hover { color:#3da1e0 } Creating … Read more
If var testint = 1; var teststr = “val”; var val1 = 5; var val2 = 8; var val3 = 4; then window[teststr + testint.toString()] will output 5 (the value of variable val1). Similarly, if var testint = 2; var teststr = “val”; var val1 = 5; var val2 = 8; var val3 = 4; … Read more