From 8fd412a1c00f5ac7228ddd88787914ac02eb28db Mon Sep 17 00:00:00 2001
From: shariyerShazan <shariyershazan1@gmail.com>
Date: Sat, 11 Apr 2026 07:22:01 +0600
Subject: [PATCH] string & some problem solving

---
 .../7_string/1_string_not_mutable_.js         | 23 ++++++++++++
 .../7_string/2_string_details_.js             | 36 +++++++++++++++++++
 .../7_string/3_check_palindrome_string_.js    | 21 +++++++++++
 .../7_string/4_toggle_upper_lowwer_.js        | 13 +++++++
 .../7_string/5_cherecter_frequency_.js        | 14 ++++++++
 .../7_string/6_cher_freq_with_map_.js         | 13 +++++++
 node-environment/7_string/7_roman_to_int_.js  | 26 ++++++++++++++
 .../7_string/8_temperateure_dif_count_.js     | 18 ++++++++++
 node-environment/7_string/9_char_count_.js    | 11 ++++++
 9 files changed, 175 insertions(+)
 create mode 100644 node-environment/7_string/1_string_not_mutable_.js
 create mode 100644 node-environment/7_string/2_string_details_.js
 create mode 100644 node-environment/7_string/3_check_palindrome_string_.js
 create mode 100644 node-environment/7_string/4_toggle_upper_lowwer_.js
 create mode 100644 node-environment/7_string/5_cherecter_frequency_.js
 create mode 100644 node-environment/7_string/6_cher_freq_with_map_.js
 create mode 100644 node-environment/7_string/7_roman_to_int_.js
 create mode 100644 node-environment/7_string/8_temperateure_dif_count_.js
 create mode 100644 node-environment/7_string/9_char_count_.js

diff --git a/node-environment/7_string/1_string_not_mutable_.js b/node-environment/7_string/1_string_not_mutable_.js
new file mode 100644
index 0000000..7b6da49
--- /dev/null
+++ b/node-environment/7_string/1_string_not_mutable_.js
@@ -0,0 +1,23 @@
+let arr = [ 0 , 39 , 93 , 45 , 32, 67 , 9 , 56]
+arr.push(100)
+console.log(arr) // [ 0 , 39 , 93 , 45 , 32, 67 , 9 , 56 , 100]
+arr[0] = 100
+console.log(arr)// [ 100 , 39 , 93 , 45 , 32, 67 , 9 , 56 , 100]
+
+
+//! but it's push pop not work in the string
+ 
+let name = "shazan"
+// name.push("f") //! error
+console.log(name) // shazan
+console.log(name[0]) // s
+console.log(name[4]) // a
+
+//! concarinate 
+let firstName = "shariyer"
+console.log(firstName + " shazan") // shariyer shazan
+
+//! or
+let fName = "atiya"
+ fName += " Priya"
+ console.log(fName) // atiya Priya
\ No newline at end of file
diff --git a/node-environment/7_string/2_string_details_.js b/node-environment/7_string/2_string_details_.js
new file mode 100644
index 0000000..66693e8
--- /dev/null
+++ b/node-environment/7_string/2_string_details_.js
@@ -0,0 +1,36 @@
+let name = "shazan";
+console.log(name.length); // 6
+
+console.log(name.slice(0, 3)); // sha
+console.log(name.slice(3, name.length)); // zan
+console.log(name.slice(-3, name.length)); // zan
+
+//! substring
+console.log(name.substring(2)); // azan
+console.log(name.substring(2, name.length - 1)); // aza
+name = name.toUpperCase();
+console.log(name); //SHAZAN
+console.log(name.toLowerCase()); // shazan
+
+console.log(name.concat(" ", "priya")); // SHAZAN priya
+console.log(name.concat(" ", "priya").toLowerCase()); // shazan priya
+
+let me = "       shariyer shazan      ";
+console.log(me); //        shariyer shazan
+console.log(me.trim()); // shariyer shazan
+
+name = name.toLowerCase();
+console.log(name.charAt(2)); // a
+console.log(name.charCodeAt(2)); // 97
+console.log("a".charCodeAt()); // 97
+console.log("A".charCodeAt()); // 65
+
+for (let i = name.length - 1; i >= 0; i--) {
+  console.log(name.charAt(i));
+}
+
+let rev = "";
+for (let i = name.length - 1; i >= 0; i--) {
+  rev += name.charAt(i);
+}
+console.log(rev) // nazahs
\ No newline at end of file
diff --git a/node-environment/7_string/3_check_palindrome_string_.js b/node-environment/7_string/3_check_palindrome_string_.js
new file mode 100644
index 0000000..8a8e21d
--- /dev/null
+++ b/node-environment/7_string/3_check_palindrome_string_.js
@@ -0,0 +1,21 @@
+import { prompt } from "../4_js_pattern/1_node_prompt_sync_.js";
+
+const str = prompt("Enter a string: ").toLowerCase().trim();
+
+console.log(str.split(""));
+console.log(str.length);
+
+let isPalindrome = true;
+let i = 0,
+  j = str.length - 1;
+
+while (i < j) {
+  if (str[i] !== str[j]) {
+    isPalindrome = false;
+    break;
+  }
+  i++;
+  j--;
+}
+
+console.log(isPalindrome ? "It's a palindrome" : "Not a palindrome"); // if mam //? It's a palindrome
diff --git a/node-environment/7_string/4_toggle_upper_lowwer_.js b/node-environment/7_string/4_toggle_upper_lowwer_.js
new file mode 100644
index 0000000..be44b94
--- /dev/null
+++ b/node-environment/7_string/4_toggle_upper_lowwer_.js
@@ -0,0 +1,13 @@
+import { prompt } from "../4_js_pattern/1_node_prompt_sync_.js";
+
+let name = prompt("Enter a string:  ")
+console.log(name) // ShAzAn
+let toggle = ""
+for(let i = 0 ; i<name.length ; i++){
+    if(name.charCodeAt(i) >= 65 && name.charCodeAt(i) <= 90){
+        toggle += name[i].toLowerCase()
+    } else{
+        toggle += name[i].toUpperCase();
+    }
+}
+console.log(toggle); // sHaZaN
\ No newline at end of file
diff --git a/node-environment/7_string/5_cherecter_frequency_.js b/node-environment/7_string/5_cherecter_frequency_.js
new file mode 100644
index 0000000..57066c0
--- /dev/null
+++ b/node-environment/7_string/5_cherecter_frequency_.js
@@ -0,0 +1,14 @@
+import { prompt } from "../4_js_pattern/1_node_prompt_sync_.js";
+
+let str = prompt("Enter a string: ").trim()
+let freq = {};
+
+for (let ch of str) {
+  if (freq[ch]) {
+    freq[ch]++;
+  } else {
+    freq[ch] = 1;
+  }
+}
+
+console.log(freq);
diff --git a/node-environment/7_string/6_cher_freq_with_map_.js b/node-environment/7_string/6_cher_freq_with_map_.js
new file mode 100644
index 0000000..b76525d
--- /dev/null
+++ b/node-environment/7_string/6_cher_freq_with_map_.js
@@ -0,0 +1,13 @@
+import { prompt } from "../4_js_pattern/1_node_prompt_sync_.js";
+
+let str = prompt("Enter a string: ").trim();
+let map = new Map();
+
+for (let ch of str) {
+  map.set(ch, (map.get(ch) || 0) + 1);
+}
+
+console.log(map);
+
+let head = [2,3,4,52,3 ,45]
+head.sort()
diff --git a/node-environment/7_string/7_roman_to_int_.js b/node-environment/7_string/7_roman_to_int_.js
new file mode 100644
index 0000000..7886c1e
--- /dev/null
+++ b/node-environment/7_string/7_roman_to_int_.js
@@ -0,0 +1,26 @@
+/**
+ * @param {string} s
+ * @return {number}
+ */
+var romanToInt = function (s) {
+  let map = {
+    I: 1,
+    V: 5,
+    X: 10,
+    L: 50,
+    C: 100,
+    D: 500,
+    M: 1000,
+  };
+  let total = 0;
+  for (let i = 0; i < s.length; i++) {
+    let current = map[s[i]];
+    let next = map[s[i + 1]];
+    if (current < next) {
+      total -= current;
+    } else {
+      total += current;
+    }
+  }
+  return total;
+};
diff --git a/node-environment/7_string/8_temperateure_dif_count_.js b/node-environment/7_string/8_temperateure_dif_count_.js
new file mode 100644
index 0000000..a3ce147
--- /dev/null
+++ b/node-environment/7_string/8_temperateure_dif_count_.js
@@ -0,0 +1,18 @@
+let temperature = [ -4 , -10 , 33 , 54 , "error",34 ,21 , 18 , -12 , -3, 8 , -9 ]
+
+let tempDiff = (tempArr) => {
+    let lower = tempArr[0]
+    let higher = tempArr[0]
+
+     for(let i = 0 ;  i< tempArr.length ; i++){
+        if(typeof  tempArr[i] !== "number"){ continue}
+        if(lower > tempArr[i]){
+            lower = tempArr[i]
+        }
+        if(higher < tempArr[i]){
+            higher = tempArr[i]
+        }
+     }
+     return higher - lower
+}
+console.log(tempDiff(temperature))
\ No newline at end of file
diff --git a/node-environment/7_string/9_char_count_.js b/node-environment/7_string/9_char_count_.js
new file mode 100644
index 0000000..7325bb7
--- /dev/null
+++ b/node-environment/7_string/9_char_count_.js
@@ -0,0 +1,11 @@
+let charCount = (chars) => {
+    let char = {}
+    for(let c of chars){
+        if(char[c]){
+            char[c]++
+        } else {
+            char[c] == 1
+        }
+    }
+    return char
+}
\ No newline at end of file