Associative Array in Javascript Key is number, but access as string (Associative)

Question

I'm attempting to create a lookup table in Javascript that is populated ahead of time by a table (basically just turning a table into a Javascript array), then, a dropdown value is referenced for the "score" column of the table.

var pointsGrid=[];

// First column is the primary key in a table with the same layou
// Second column is the name of the move
// Third column is the score
pointsGrid.push(['1',"Run",0.1]);
pointsGrid.push(['2',"Jump",0.5]);
pointsGrid.push(['3',"Twist",0.9]);

<select id="moveSelect">
  <option value="1">Run</option>
  <option value="2">Jump</option>
  <option value="3">Twist</option>
</select>

My question is during the onChange event, when I read the value of the dropdown, how do I reference the array by string, instead of by number?

For example: pointsGrid["1"] not pointsGrid[1], like in pointsGrid["StringKey"]? It keeps going back to pointsGrid[1] which is pulling the wrong score value.

Thank you in advance, Dan Chase

I think you want an Object, not an Array. Arrays are Objects which are specialized for sequential, data. In any case, you can use either a string or a number with bracket notation [stringOrNumber]. A number will be converted to a string. — Aluan Haddad
– Aluan Haddad, Commented May 7, 2017 at 6:26
var pointsGrid[]; is a syntax error. I think you're missing an equals-sign? — Raymond Chen
– Raymond Chen, Commented May 7, 2017 at 6:28
Raymond, corrected the typo, thank you. In the program it's correct. — Dan Chase
– Dan Chase, Commented May 7, 2017 at 6:30

marmeladze · Accepted Answer · 2017-05-07 06:31:31Z

2

Arrays number-indexed data structures. Use objects instead.

var pointsGridObj = {}
pointsGridObj["1"] = ["Run", "0.1"]
pointsGridObj["2"] = ["Jump", "0.5"]
pointsGridObj["3"] = ["Twist", "0.9"]

Or if you have the triples as an array,

pointsGridobj = {}; 
for(var i=0; i<pointsGrid.length; i++) {
  pointsGridobj[pointsGrid[i][0]] = pointsGrid.slice(1,3);
}

answered May 7, 2017 at 6:31

marmeladze

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