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you can redeclare undefined using scope wrappers: (function($, undefined){ /* undefined is 'abc' in here */ })(jQuery, 'abc');, which is why ppl complain that it's technically not safe unless you're 100% sure you know where your code is being run.
console.log(getTagNames(tags)); // 'undefined'. function getTagNames(tagArray) {. $.getJSON('js/tags.json', function(data) {. for (var i in tagArray) {. tagArray[i] = tagArray[i].toString(); var val = tagArray[i]; for (var t in data) {. var tag = data[t]; var tagName = tag.alias;
25 lip 2024 · A variable that has not been assigned a value is of type undefined. A method or statement also returns undefined if the variable that is being evaluated does not have an assigned value. A function returns undefined if a value was not returned.
23 mar 2023 · console.log (myVariable); // => undefined. myVariable is declared and not yet assigned with a value. Accessing the variable evaluates to undefined. An efficient approach to solve the troubles of uninitialized variables is whenever possible to assign an initial value.
What is undefined. The undefined is a primitive type in JavaScript. So the undefined is a type. And the undefined type has exactly one value that is undefined. JavaScript uses the undefined value in the following situations. 1) Accessing an uninitialized variable.
19 maj 2017 · A variable that has not been assigned a value is of type undefined. A method or statement also returns undefined if the variable that is being evaluated does not have an assigned value. A function returns undefined if a value was not returned.
11 lip 2022 · When a variable is declared or initialized but no value is assigned to it, JavaScript automatically displays "undefined". It looks like this: let myStr; console.log(myStr); // undefined. Also, when you try accessing values in, for example, an array or object that doesn’t exist, it will throw undefined. let user = {.
