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THE APEX INSTITUTE · GORAKHPUR

JavaScript Complete Notes

English + Hindi · Theory · Practical Code · Expected Output

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Learn by reading, running, and changing code

Read the English explanation and Hindi explanation, run a practical, then change one value and predict the result before running it again.

English और Hindi में explanation पढ़ें, practical चलाएँ, फिर एक value बदलकर दोबारा run करने से पहले output का अनुमान लगाएँ।

Additional practicals from uploaded files / अपलोड की गई फाइलों के अतिरिक्त practicals

Includes popup boxes, user-input addition, calculator, form validation, confirmation before delete, student registration form, and AngularJS examples.

Open additional practicals →

Important corrections / ज़रूरी सुधार

  • Use const and let: Prefer them over var in modern code. / आधुनिक code में सामान्यतः var के बजाय const और let प्रयोग करें।
  • Equality: Prefer === and !== to avoid unwanted type conversion. / अनचाहे type conversion से बचने के लिए === और !== प्रयोग करें।
  • Date methods: getMonth() returns 0–11; getDay() returns weekday index; getDate() returns day of month.
  • DOM replacement: replaceChild(newNode, oldNode) takes the new node first. / replaceChild() में नया node पहले आता है।
  • Timers: Cancel setTimeout() with clearTimeout() and setInterval() with clearInterval().
  • Safe text: Use textContent for user-entered text rather than inserting it as HTML. / User का text दिखाने के लिए textContent उपयोग करें।
  • localStorage: Stores strings; do not store passwords or secrets there. / इसमें password या sensitive जानकारी न रखें।