Initialization in variable declarations against recommended approach JS-0119
Anti-pattern
Minor
8 months ago
—
a year old
Variable 'option' should be initialized on declaration
3806 this.onKeyDown = (function() {
3807 var original = self.onKeyDown;
3808 return function(e) {
3809 var index, option;3810 if (e.keyCode === KEY_BACKSPACE && this.$control_input.val() === '' && !this.$activeItems.length) {
3811 index = this.caretPos - 1;
3812 if (index >= 0 && index < this.items.length) {Variable 'index' should be initialized on declaration
3806 this.onKeyDown = (function() {
3807 var original = self.onKeyDown;
3808 return function(e) {
3809 var index, option;3810 if (e.keyCode === KEY_BACKSPACE && this.$control_input.val() === '' && !this.$activeItems.length) {
3811 index = this.caretPos - 1;
3812 if (index >= 0 && index < this.items.length) {Variable 'i' should be initialized on declaration
3654 };
3655
3656 var equalizeSizes = function() {
3657 var i, n, height_max, width, width_last, width_parent, $optgroups;3658
3659 $optgroups = $('[data-group]', self.$dropdown_content);
3660 n = $optgroups.length;Variable 'n' should be initialized on declaration
3654 };
3655
3656 var equalizeSizes = function() {
3657 var i, n, height_max, width, width_last, width_parent, $optgroups;3658
3659 $optgroups = $('[data-group]', self.$dropdown_content);
3660 n = $optgroups.length;Variable 'height_max' should be initialized on declaration
3654 };
3655
3656 var equalizeSizes = function() {
3657 var i, n, height_max, width, width_last, width_parent, $optgroups;3658
3659 $optgroups = $('[data-group]', self.$dropdown_content);
3660 n = $optgroups.length;
Description
In JavaScript, variables can be assigned during declaration, or at any point afterwards using an assignment statement. For example, in the following code, foo is initialized during declaration, while bar is initialized later.
var foo = 1;
var bar;
if (foo) {
bar = 1;
} else {
bar = 2;
}
Bad Practice
function foo() {
var bar;
let baz;
}
Recommended
function foo() {
var bar = 1;
let baz = 2;
const qux = 3;
}