https://en.netcup.nllk.net/blog/categories/javascript/ Recent content in javascript on netcup hosting blog Hugo -- gohugo.io en Mon, 31 Aug 2026 00:00:00 +0000 https://en.netcup.nllk.net/blog/post/0071-javascript-closures/ Mon, 31 Aug 2026 00:00:00 +0000 https://en.netcup.nllk.net/blog/post/0071-javascript-closures/ This article shows what a JavaScript closure is, why two counters from the same factory do not share state, why var in a loop gives you the same number three times, and what a closure keeps alive. https://en.netcup.nllk.net/blog/post/0077-javascript-string-to-boolean/ Mon, 31 Aug 2026 00:00:00 +0000 https://en.netcup.nllk.net/blog/post/0077-javascript-string-to-boolean/ This article shows why Boolean("false") is true, what JSON.parse does to "1" and "yes", and how to write a converter that decides what unknown input means instead of guessing. https://en.netcup.nllk.net/blog/post/0075-javascript-uuid/ Mon, 31 Aug 2026 00:00:00 +0000 https://en.netcup.nllk.net/blog/post/0075-javascript-uuid/ This article shows how to generate a UUID with crypto.randomUUID, what the version and variant digits mean, why the Math.random one-liner is not a substitute, and why randomUUID is undefined on plain http. https://en.netcup.nllk.net/blog/post/0079-javascript-deep-clone/ Mon, 31 Aug 2026 00:00:00 +0000 https://en.netcup.nllk.net/blog/post/0079-javascript-deep-clone/ This article shows what structuredClone keeps that the JSON round-trip destroys, what structuredClone silently drops, and a timing where the JSON version is the faster one. https://en.netcup.nllk.net/blog/post/0073-javascript-include-another-file/ Mon, 31 Aug 2026 00:00:00 +0000 https://en.netcup.nllk.net/blog/post/0073-javascript-include-another-file/ This article shows how import, require and dynamic import() differ, why a module body runs only once, and why most 'is not defined' errors are really a script order problem. https://en.netcup.nllk.net/blog/post/0072-javascript-remove-array-item/ Mon, 31 Aug 2026 00:00:00 +0000 https://en.netcup.nllk.net/blog/post/0072-javascript-remove-array-item/ This article shows the difference between filter and splice when removing an array item, why the missing -1 check deletes the wrong element, and why delete leaves a hole. https://en.netcup.nllk.net/blog/post/0076-javascript-round-2-decimals/ Mon, 31 Aug 2026 00:00:00 +0000 https://en.netcup.nllk.net/blog/post/0076-javascript-round-2-decimals/ This article compares toFixed and Math.round(x*100)/100 over 100,000 values, shows why 1.005 rounds down, and why toFixed and Intl.NumberFormat disagree on the same number. https://en.netcup.nllk.net/blog/post/0078-javascript-sleep/ Mon, 31 Aug 2026 00:00:00 +0000 https://en.netcup.nllk.net/blog/post/0078-javascript-sleep/ This article shows the promise-based sleep, measures what a busy-wait costs a pending timer, and why forEach with an async callback does not wait at all. https://en.netcup.nllk.net/blog/post/0074-javascript-validate-email/ Mon, 31 Aug 2026 00:00:00 +0000 https://en.netcup.nllk.net/blog/post/0074-javascript-validate-email/ This article compares a popular email regex with a loose one and with the browser's own check on the same ten inputs, and shows they disagree on half of them. https://en.netcup.nllk.net/blog/post/0080-javascript-function-declaration-vs-expression/ Mon, 31 Aug 2026 00:00:00 +0000 https://en.netcup.nllk.net/blog/post/0080-javascript-function-declaration-vs-expression/ This article shows what hoisting does to a function declaration and a function expression, why var and const give different errors, and why naming a function expression for the stack trace is mostly obsolete.