How to make Array.indexOf() case insensitive in JavaScript ?
The task is to make the Array.indexOf() method case insensitive. Here are a few of the most techniques discussed with the help of JavaScript.
The .toLowerCase() method: Transform the search string and elements of the array to the lower case using .toLowerCase() method, then perform the simple search. Below example illustrate the method.
Example 1:
<!DOCTYPE HTML> < html > < head > < title > How to use Array.indexOf() case insensitive in JavaScript ? </ title > </ head > < body style = "text-align:center;" > < h1 style = "color: green" > Geeksforgeeks </ h1 > < p id = "GFG_UP" style = "font-size: 20px;font-weight: bold;" > </ p > < button onclick = "gfg_Run()" > Click Here </ button > < p id = "GFG_DOWN" style="color:green; font-size: 26px; font-weight: bold;"> </ p > < script > var el_up = document.getElementById("GFG_UP"); var el_down = document.getElementById("GFG_DOWN"); var arr = ['GFG_1', 'geeks', 'Geeksforgeeks', 'GFG_2', 'gfg']; var el = 'gfg_1'; el_up.innerHTML = "Click on the button for " + "case-insensitive search. < br >Array = '" + arr + "'< br >Element = '" + el + "'"; function gfg_Run() { res = arr.findIndex(item => el.toLowerCase() === item.toLowerCase()); el_down.innerHTML = "The index of '" + el + "' is '" + res + "'."; } </ script > </ body > </ html > |
Output:
The .toUpperCase() method: Transform the search string and elements of the array to the upper case using .toUpperCase() method, then perform the simple search. Below example illustrates this method.
Example 2:
<!DOCTYPE HTML> < html > < head > < title > How to use Array.indexOf() case insensitive in JavaScript ? </ title > </ head > < body style = "text-align:center;" > < h1 style = "color: green" > GeeksforGeeks </ h1 > < p id = "GFG_UP" style="font-size:20px; font-weight: bold;"> </ p > < button onclick = "gfg_Run()" > Click Here </ button > < p id = "GFG_DOWN" style="color:green; font-size: 26px; font-weight: bold;"> </ p > < script > var el_up = document.getElementById("GFG_UP"); var el_down = document.getElementById("GFG_DOWN"); var arr = ['GFG_1', 'geeks', 'GeeksforGeeks', 'GFG_2', 'gfg']; var el = 'gfg_1'; el_up.innerHTML = "Click on the button for " + "case-insensitive search. < br >Array = '" + arr + "'< br >Element = '" + el + "'"; function gfg_Run() { var res = arr.find(key => key.toUpperCase() === el.toUpperCase()) != undefined; if (res) { res = 'present'; } else { res = 'absent'; } el_down.innerHTML = "The element '" + el + "' is '" + res + "' in the array."; } </ script > </ body > </ html > |
Output: