Please explain the purpose of the .forEach statements listed below

Question

Please explain the purpose of the .forEach statements listed below

Describe the functionality of the two forEach loops provided in the code snippet below. Also, is 'col' a predefined property for arrays?

var width = data.length, height = data[0].length;
    data.forEach(function(col){
    col.forEach(function(val){
        geometry.vertices.push(new THREE.Vector3(val.x,val.y,val.z))
        colors.push(getColor(2.5,0,val.z));
    });
    });

In case you need to reference the initial code:

var data = new Array();
    for(var x=BIGIN;x<END;x++){
    var row = [];
    for(var y=BIGIN;y<END;y++){
        z = 2.5*(Math.cos(Math.sqrt(x*x+y*y))+1);
        row.push({x: x, y: y, z: z});
    }
    data.push(row);
    }

javascript three.js

Answer 1

Answer №1

Array.forEach is a method that loops over an array, similar to a for loop.

array.forEach(function( indice ) {});

data consists of an array of arrays, where col is the parameter passed from the first forEach function, allowing the second forEach to loop through arrays within data.

This structure is evident in the code that generates data

var data = []; // data is an array
...
var row = [];  // row is an array
for(var ...){
    // do stuff
}
data.push(row); // inserts one array inside another

Subsequently, it is iterated as follows:

data.forEach(function(col){ // <- col is passed as the parameter
    col.forEach(function(val){
        // do stuff
    });
});

Answer 2

Array.forEach is a method that loops over an array, similar to a for loop.

array.forEach(function( indice ) {});

data consists of an array of arrays, where col is the parameter passed from the first forEach function, allowing the second forEach to loop through arrays within data.

This structure is evident in the code that generates data

var data = []; // data is an array
...
var row = [];  // row is an array
for(var ...){
    // do stuff
}
data.push(row); // inserts one array inside another

Subsequently, it is iterated as follows:

data.forEach(function(col){ // <- col is passed as the parameter
    col.forEach(function(val){
        // do stuff
    });
});

Please explain the purpose of the .forEach statements listed below

Answer №1

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