Default parameters make function parameters more flexible.
Default parameters make function parameters more flexible
define it using an assignment to the parameter function(param=1){}
let aNumber = (int) => int;
assert.equal(aNumber(), 0);it is used when undefined is passed
let aNumber = (int = 23) => int;
const param = 42;
assert.equal(aNumber(param), 23);it is not used when a value is given
function xhr() {
return method;
}
assert.equal(xhr('POST'), 'POST');it is evaluated at run time
let defaultValue;
function xhr(method = `value: ${defaultValue}`) {
return method;
}
assert.equal(xhr(), 'value: 42');it can also be a function
const defaultValue = 0;
function fn(value = defaultValue()) {
return value;
}
assert.equal(fn(), 'defaultValue');