Javascript Searching Array for partial string

Question

Have a function that returns an array of objects. The array has a rate object that has a name field. Inside the name field are names such as "Slow speed" and "Fast speed".

I have written the following in hopes to create a new array that will filter out the array values and just return only those with "Slow" that matches from the rates[i].name.

So far I am encountering this error in my dev console. "Uncaught TypeError: value.substring is not a function"

var rates = myArray();
var index, value, result;
var newArr = [];

for (index = 0; index < rates.length; ++index) {
    //value = rates[index];
    if (value.substring(0, 5) === "Stand") {
        result = value;
        newArr.push();
        break;
    }
}

Part of array return in console.

"rates":[{"id":1123,"price":"1.99","name":"Slow speed - Red Car","policy":{"durqty":1,"durtype":"D","spdup":15000,"spddwn":15000}

Possible duplicate of [In javascript, how do you search an array for a substring match](http://stackoverflow.com/questions/4556099/in-javascript-how-do-you-search-an-array-for-a-substring-match) — Rathma, Jul 23 '16 at 04:01
value is an object at particular index of arrray. You may need to do `value.name` — Ajay Narain Mathur, Jul 23 '16 at 04:04
Don't `break;` if you want `newArr` to store more than just the first match. — 4castle, Jul 23 '16 at 04:06

sasidhar · Accepted Answer · 2016-07-23T04:13:44.933

4

You have an object at each array location not the string itself, try this instead:

var rates = myArray();
var index, value, result;
var newArr = [];

for (index = 0; index < rates.length; ++index) {
    name = rates[index].name;
    if (name.substring(0, 4) === "Slow") {
        newArr.push(rates[index]);
    }
}

Try using filter function like this, it is much more cleaner to see

var newArr = rates.filter(function(rate){
  return rate.name && rate.name.substring(0,4) === "Slow";
});

edited Jul 23 '16 at 04:13

answered Jul 23 '16 at 04:07

sasidhar

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The first 4 characters would be under `substring(0, 4)` – 4castle Jul 23 '16 at 04:10
you give value to `name`, then check for `value.substring`, also when `substring(0,5)` returns word with whitespace `"Slow "` so it won't match `"Slow"` – moped Jul 23 '16 at 04:11
Yup you are right, my bad. Was editing his code, didn't pay attention. Thanks, edited – sasidhar Jul 23 '16 at 04:12

Titus · Answer 2 · 2016-07-23T04:15:37.547

1

You can use filter to do this, for example:

var newArr = rates.filter(function(val){
    // check if this object has a property `name` and this property's value starts with `Slow`.
    return val.name && val.name.indexOf("Slow") == 0; 
});

As @4castle mentioned, instead of indexOf(...) you can use slice(...) which may be more efficent, eg: val.name.slice(0,4) == "Slow"

edited Jul 23 '16 at 04:15

answered Jul 23 '16 at 04:07

Titus

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`indexOf` will look at the whole string. If they just want to look at the first 4 characters, they should use `slice(0, 4) === "Slow"` – 4castle Jul 23 '16 at 04:08

Javascript Searching Array for partial string

2 Answers2

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