Javascript error 'has no method push'

Question

I'm getting the error: object 0 has no method 'push', and I can't figure out why.

I know that sack[i] is the object, i is 0 and quantity_to_spawn equals 1.

I think that node has an issue with pushing because sack is an array and sack[i] is actually an object.

for (i=0;i<rows[r].quantity_to_spawn;i++){
 more_drops = Math.random()
 sack[i]=new Array();
 for (;more_drops > .05;){
 more_drops = Math.random()
 rarity = Math.random()
 if (rarity <= .75&&typeof rows[r].common=="string"){//common drop 75%
 item=rows[r].common.split(",")
 sack[i].push(parseInt(item[parseInt(Math.random()*item.length)]))
 ...

• ZachB: Are you declaring sack before the outer for loop as an array?
• Anthony Mills: I'd be more comfortable if I saw a few var keywords in there...
• epascarello: Use semicolons, they should not be optional. Why does it seem everything is also global?
• epascarello: Also your random times length is going to give issues when Random returns one.
• Vlad: Add var sack = []; before the first for.

Answer 1

I'm sure you are missing to declare the variable sack as an array,

var sack = new Array();

or

var sack = [];

Otherwise it should work

Here is the simple demo

I made some experiment regard to this problem, found some interesting facts. Those are,

The problem is sack is already assigned something like var sack = 'someValue';. in this case (assigned value string type), this resulting in sack to be a string array. Hence the assignment sack[i]=new Array(); make no sense. sack[0] will be s. and try to push some value to this will throw the error object 0 has no method 'push'

Another case(assigned value number type), assignment is like var sack = 28892;. In this case, the same array assignment making no sense. But if you try to push something to sack[0] it will throw Cannot call method 'push' of undefined, since sack[0] is undefined.

In both cases, after declaring sack to some value, the assignment not produced any error, though it is useless.

Additional information about array declaration,

Javascript array declaration: new Array(), new Array(3), ['a', 'b', 'c'] create arrays that behave differently

• Teemu: This can't be the issue. If it was, there would be sack is undefined thrown just before the second for loop.
• code-jaff: @Teemu no, what will happen if the variable defined as var sack;, obviously there would be no such error.
• Teemu: In that case the error would be Can't set property 0, object is null or undefined in line sack[i]=new Array();. There's no way to execute code past this line, if sack is not an array. OP's having this error: object 0 has no method push, this tells that object (=== sack[0]) exists, but there's not method called push in that object.

Answer 2

No idea what you are doing here, but try this:

var sack = [];
for (var i=0;i<rows[r].quantity_to_spawn;i++) {
 var more_drops = Math.random();
 sack[i] = [];
 for (;more_drops > 0.05;) {
 more_drops = Math.random();
 var rarity = Math.random();
 if (rarity <= 0.75&&typeof rows[r].common==="string") {//common drop 75%
 var item = rows[r].common.split(",");
 sack[i].push(parseInt(item[parseInt(Math.random()*item.length,10)],10));
 ... 

• Teemu: This can't be the issue. If it was, there would be sack is undefined thrown just before the second for loop.