Unable to find if a string contains a substring?

Question

I am trying to have sql's like clause like effect in javascript.

I am aware that similar question are already present on internet but the following approach is not working for me:

$(document).ready(function() {
  var listAll = [
    "X1",
    "ANTENNA SYSTEMS          00000000AS",
    "Security & Wrokf         00000000CS",
    "MICROWAVE & COMM         00000000MC",
    "MICROWAVE SENSOR         00000000MT",
    "PLANNING & PROJE         00000000PG",
    "MECHANICAL SYSTE         00000000MS",
    "ELECTRO-OPTICAL          00000000EO",
    "SATCOM EXPERIMEN         00000000SE",
    "QUALITY ASSURANC         00000000QA",
    "QUALITY ASSURANC         00000000QC",
    "DATA PRODUCTS SO         00000000DP"
  ];
  var lstfiltered = ["X2"];

  for (i = 0; i <= listAll.length - 1; i++) {
    console.log(listAll[i]);
    var string = listAll[i];
    var substring = "lan";
    if (string.indexOf(substring) !== -1) {
      lstfiltered.push(string);
    }
  }

  console.log(lstfiltered);
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>

I have set substring which is to be looked up in string as "lan", which should push "PLANNING & PROJE 00000000PG" into the array. But it does not.

case sensitive?try changing to lowercase first before compare? — guradio
– guradio, Commented Nov 14, 2016 at 11:50
toLowerCase() to make it case insensitive or you can use localeCompare() to compare the string — Black Mamba
– Black Mamba, Commented Nov 14, 2016 at 11:59

Abhishek Dhanraj Shahdeo · Accepted Answer · 2016-11-14 11:53:59Z

2

I think that the problem is with the letter casing. Try this :

$(document).ready(function() {
  var listAll = ["X1", "ANTENNA SYSTEMS          00000000AS", "Security & Wrokf         00000000CS", "MICROWAVE & COMM         00000000MC", "MICROWAVE SENSOR         00000000MT", "PLANNING & PROJE         00000000PG", "MECHANICAL SYSTE         00000000MS", "ELECTRO-OPTICAL          00000000EO", "SATCOM EXPERIMEN         00000000SE", "QUALITY ASSURANC         00000000QA", "QUALITY ASSURANC         00000000QC", "DATA PRODUCTS SO         00000000DP"];
  var lstfiltered = ["X2"];
  
  for (i = 0; i <= listAll.length - 1; i++) {
    console.log(listAll[i]);
    var string = listAll[i];
    var substring = "lan";
    if (string.toLowerCase().indexOf(substring) !== -1) {
      lstfiltered.push(string);
    }
  }

  console.log(lstfiltered);
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>

edited Nov 14, 2016 at 11:53

answered Nov 14, 2016 at 11:51

Abhishek Dhanraj Shahdeo

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1 Comment

Abhishek Dhanraj Shahdeo Over a year ago

Damn it, I know. All we need to take care is to convert either into lowercase or uppercase for comparison.

Nina Scholz · Accepted Answer · 2016-11-14 12:03:06Z

I suggest to search for lower case letters and move the search string outside of the loop.

$(document).ready(function() {
  var listAll = ["X1", "ANTENNA SYSTEMS          00000000AS", "Security & Wrokf         00000000CS", "MICROWAVE & COMM         00000000MC", "MICROWAVE SENSOR         00000000MT", "PLANNING & PROJE         00000000PG", "MECHANICAL SYSTE         00000000MS", "ELECTRO-OPTICAL          00000000EO", "SATCOM EXPERIMEN         00000000SE", "QUALITY ASSURANC         00000000QA", "QUALITY ASSURANC         00000000QC", "DATA PRODUCTS SO         00000000DP"];
  var lstfiltered = ["X2"];
  var substring = "lan";
  
  for (i = 0; i <= listAll.length - 1; i++) {
    console.log(listAll[i]);
    var string = listAll[i];
    if (string.toLowerCase().indexOf(substring) !== -1) {
      lstfiltered.push(string);
    }
  }

  console.log(lstfiltered);
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>

For a more concise version, you could use Array#filter

$(document).ready(function() {
  var listAll = ["X1", "ANTENNA SYSTEMS          00000000AS", "Security & Wrokf         00000000CS", "MICROWAVE & COMM         00000000MC", "MICROWAVE SENSOR         00000000MT", "PLANNING & PROJE         00000000PG", "MECHANICAL SYSTE         00000000MS", "ELECTRO-OPTICAL          00000000EO", "SATCOM EXPERIMEN         00000000SE", "QUALITY ASSURANC         00000000QA", "QUALITY ASSURANC         00000000QC", "DATA PRODUCTS SO         00000000DP"];
  var substring = "lan";
  var lstfiltered = listAll.filter(function (a) {
          return a.toLowerCase().indexOf(substring) !== -1;
      });

  lstfiltered.unshift('X2')
  console.log(lstfiltered);
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>

Ayush Nawani · Accepted Answer · 2016-11-14 12:01:17Z

If you want to push original string then compare with string converted by using toLowerCase() and push the original string as shown below :

 $(document).ready(function() {

   var listAll = ["X1", "ANTENNA SYSTEMS          00000000AS", "Security & Wrokf         00000000CS", "MICROWAVE & COMM         00000000MC", "MICROWAVE SENSOR         00000000MT", "PLANNING & PROJE         00000000PG", "MECHANICAL SYSTE         00000000MS", "ELECTRO-OPTICAL          00000000EO", "SATCOM EXPERIMEN         00000000SE", "QUALITY ASSURANC         00000000QA", "QUALITY ASSURANC         00000000QC", "DATA PRODUCTS SO         00000000DP"];

   var lstfiltered = ["X2"];




   for (i = 0; i <= listAll.length - 1; i++) {
     console.log(listAll[i]);

     var string = listAll[i].toLowerCase();

     var substring = "lan";
     if (string.indexOf(substring) !== -1) // compare with string converted by toLowerCase() 
       {

       lstfiltered.push(listAll[i]); // Push original string.

     }
   }

   console.log(lstfiltered);


 });

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