The map.get() function in D3.js is used to return the value for the specified key string. If the created map does not contain the specified key then it returns undefined.
Syntax:
map.get(key)
Parameters: This function accepts single parameter key which is used to specify the key string.
Return Value: This function returns the value for the specified key string. If the created map does not have an entry for the specified key, returns undefined.
Below programs illustrate the d3.map.get() function in D3.js:
Example 1:
<!DOCTYPE html> <html> <head> <title>d3.map.get() function</title>
</head> <body> <script>
// Creating a map
var map = d3.map({"Ram": 5});
// Calling the map.get() function
A = map.get("Ram");
// Getting the value for the "Ram" key
console.log(A);
</script>
</body> </html> |
Output:
5
Example 2:
<!DOCTYPE html> <html> <head> <title>d3.map.get() function</title>
</head> <body> <script>
// Creating a map
var map1 = d3.map({"Ram": 5});
var map2 = d3.map({"Geeks": 10});
var map3 = d3.map({"Ram": 5}, {"Geeks": 10});
var map4 = d3.map();
// Calling the map.get() function
A = map1.get("Ram");
B = map2.get("Geeks");
C = map3.get("Geeks");
D = map3.get("Ram");
E = map4.get("Geeks");
// Getting the values for
// the specified keys
console.log(A);
console.log(B);
console.log(C);
console.log(D);
console.log(E);
</script>
</body> </html> |
Output:
5 10 undefined 5 undefined
Ref: https://devdocs.io/d3~5/d3-collection#map_get