I created a function for getting last child element using TypeScript.
If I use normal if/else typescript not raising any error.
function lastChildElement(element: HTMLElement) {
let lastChild = element.lastChild
while (lastChild && lastChild.nodeType != 1) {
if (lastChild.previousSibling) {
lastChild = lastChild.previousSibling
} else {
break
}
}
return lastChild
}
but when using ternary/conditional expression
function lastChildElement(element: HTMLElement) {
let lastChild = element.lastChild
while (lastChild && lastChild.nodeType != 1) {
lastChild.previousSibling ? lastChild = lastChild.previousSibling : break
}
return lastChild
}
typescript underlining break keyword and raising Expression expected.
The conditional operator evaluates to a value. That is, if you have
someExpression ? someOtherExpression : yetAnotherExpression
The entire thing will then evaluate to either someOtherExpression or yetAnotherExpression.
But break is not a value - it's not an expression - it's a statement that can't be evaluated as anything, so it's not permitted in the context where an expression is expected.
For similar reasons, you can't do:
while (someCondition) {
const something = break;
// ...
which just doesn't make sense.
Use if/else, so that you can break as a standalone statement if needed.
That said, a better alternative to iterating through all children is to select the last element child directly.
const lastChildElement = (element: HTMLElement) => element.lastElementChild;
No loops needed.